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Firefox makes computer freeze or hang?

Friday, July 06, 2007
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The quickie

If your computer's not responding or locks up from time to time when your Firefox browser is open, but works fine after you've closed Firefox, a possible tip is to consider reverting to an older version of Firefox (older than, as Firefox seems to be behind some weird computer freezing problems lately. However you need to weigh up whether that's worth the security risks of having an outdated version - personally I felt it was, for me; but in relation to your own system the decision is entirely yours.

UPDATE: this fix was only temporary, it started freezing again after a few weeks. However, I have since found a fix that works longer term - creating a new Firefox profile.

The long and slow

These last 2 or 3 weeks, my computer has been freezing every few seconds. I could move the mouse, I could even click, but nothing would happen when I clicked a link or the taskbar or quicklaunch toolbar etc, and as for trying to use the keyboard e.g. Alt-Tab, zilch, nada, no response whatsoever. Occasionally I got the telltale couple of complaining beeps from the computer that meant "Something's too much for me to handle, gimme a chance, I'm only a poor lil machine!" My computer's fan would also whirr and churn madly for seconds at a time or longer during the freezes; I suspect the hard drive was thrashing and flailing like mad too, but I couldn't hear it over the fan.

As it happened, I found that the computer locking up from time to time was down to two unrelated issues: WinPatrol, and Firefox. I saw from Scoble that Mac users were having trouble with Fox at about the same time I'd been having problems with it, too - I commented there myself to vent a little and to point out that XP users are having trouble with Firefox too. Seems to me it can't be a coincidence, I've heard other people are also having difficulties with Firefox.

Here's my story of the troubleshooting detective work I had to do to figure out what was causing the lockups, in the hope that it may help someone else with similar issues.


I'd recently decided to give the free anti-malware software WinPatrol another try. Bad mistake - my system clearly doesn't get on well with it. By dint of downloading the free FileMon, opening it and watching while my apps did their stuff, I pinpointed which processes were accesssing or writing to files a lot. They were mostly anti-spyware software like WinPatrol.

With good ol' fashioned Ctrl Alt Delete to get at the task manager, I then killed the processes I'd identified, one by one, and saw what happened after each one. I noticed that when I stopped WinPatrol the computer stopped freezing.

So, I uninstalled WinPatrol, and all was fine and dandy for all of a few days. Then, my computer started inexplicably hanging from time to time again. The freezes became more and more frequent and each lasted for seconds at a time, even half a minute or more. As you can imagine, it drove me nuts, and I couldn't even write a blog post properly (even though I've been too busy to do much on the blog lately) as I absolutely rely on the Greasemonkey extension and various userscripts for Blogger like the keep current time on drafts, large post editor, template enlarger, font prettifier and Technorati tags tagger.

It was a mystery. According to the task manager Processes tab, the biggest user of CPU was the oh so helpful (not) "System Idle Process". Looking at memory usage didn't shed any further light on anything either. Nor did trying to use FileMon or the equally valuable and free Process Explorer. (I'm sure many others would have been able to get to the bottom of the problem from all those diagnostic tools, but I couldn't.)

But I did know that since I upgraded to Firefox it had been hogging memory, using ridiculous amounts like 400 MB, and needing restarts to stop that, whereupon it would just start eating up memory all over again. Plus I'd started getting the "unresponsive script" warning as standard whenever I launched Firefox.

So, I had my suspicions about Fox, but I started experimenting with just having a few apps open at a time, or even just one or two, and seeing what happened.

Firefox = the bad guy!

I noticed that the freezes only happened when Firefox was open - in fact the Firefox freezes were what I noticed first. More accurately, if Firefox was left open on a blank page, everything was fine. But if I tried to go to any Webpage (or just leave a Webpage open) in Firefox, everything would start hanging again. And not just Firefox hangs - my entire computer froze as well. I couldn't use any of the other apps I had open, etc, until it unfroze. If I shut down Firefox, everything would still keep freezing on and off for a little while after, but give it a few minutes and all would be working smoothly again.

I had no similar problem with Internet Explorer or Opera, even with the same Webpages. So now I knew the bad guy was Firefox. Or something on my system which didn't like Firefox.

Because of the unresponsive script issue, I also tried increasing dom.max_script_run_time but that didn't stop the unresponsive script warnings, on my system anyway, and didn't affect the freezes either, so I changed it back to the default 5.

Then I tried disabling my beloved Firefox extensions (aka add-ons), in groups at a time, then restarting Firefox, seeing if it was still freezing, disabling more extensions, seeing how it behaved after that, etc, until I was left with none at all. And guess what? Everything was still freezing every few seconds - if Firefox was open on a webpage. Shut Firefox down, or give it just a blank page to look at or nothing at all, and everything else would start behaving again after a couple of minutes.

At that point I wailed a lot and went and had some comfort ice cream. I was very controlled, I didn't throw anything, and I still have some hair left too.

Finally, I tried some more Google searches for Firefox problems, and I noticed that people were saying that the version I had,, was known for its problems including the memory issues.

So I went and downloaded an older version of Firefox -, and simply installed it (it installed neatly over and didn't affect my add-ons, history, or bookmarks etc even though I was effectively downgrading).

And how was it for me?

Voila, my computer no longer keeps hanging or freezing. I can have loads of tabs open on Fox at once, and it still doesn't take up as much memory as did. Everything is humming along quietly, as good as gold. I should point out I've not tried, I just decided to rewind beyond more than one step - ain't broke as far as freezes are concerned and that's good enough for me, I've wasted enough time on all this, I don't intend to spend any more trying to test out!

The only thing of course is that the older versions of Firefox are less secure and have vulnerabilities which were fixed in later versions. Plus I keep getting the occasional popup saying my version of Fox is out of date and recommending that I update to the latest version. No way, Firehosé! (yeah, terrible pun even for me, I know, I know). Frankly, I'd rather just live with the popups and the security risks, than the frustrating slowdowns I've had due to the inexplicable freezes. I'll just have to watch what sites I visit (and anything possibly dodgy I'll probably try to visit only via Opera with Javascript etc turned off).

I still don't know if it's something to do with Firefox itself, or if an update to one of my anti-spyware/anti-adware programs has taken a dislike to Firefox. (I had previously tried disabling Microsoft Windows Defender as I recall it had downloaded some updates recently and, call me a cynic, it seemed the most likely of my anti-malware programmes to have been set up to be anti-Firefox, but that didn't seem to do the trick.) It seems to me that something has to have changed with some commonly-used software recently, whether Firefox or something else, for so many people to all suddenly have this issue at around the same time.

So, I'm still stumped. It's a shame as I love Firefox and think it's the best all-round browser, even though Opera is faster (). I plan to keep using Firefox as my main browser. But I'm sticking with version for now - it's such a relief to be able to use my favourite browser properly again and not kill the rest of my system while I'm at it. I know there are all sorts of reasons why your computer can stop responding but if you think your Firefox is misbehaving too, and causing system hangs or system freezes, whether you're on XP or a Mac or Linux, please post a comment, I'd be interested to know how widespread the problem is. And if reverting to an older version of Fox sorted it for you too (bearing in mind the warning about security issues so do that at your own risk), do let me know.

And if anyone figures out why Firefox is generally causing problems for so many people on different systems, and even better how to fix it, please please tell me!

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17 Comment(s):

I must say you are significantly more tech savvy than I! This is an adjunct issue really to your theme however I have gone back and forth between PC and Mac and have finally settled - happily - with Mac and I use Firefox.

What frustrates me are the number of sites I encounter that have not been Mac tested principally and then Firefox tested as a secondary issue. I have found a number of sites offering hotkeys for PC but don't realise these don't always carry over to Mac. I completed a consultancy task for someone recently that required text checks and editing through themes in an exel file. Half of the 'user key' instructions for formatting they offered were incorrect for my Mac system. I wound up not only doing the task but also offering them a small user Mac manual.

I have used various news service archive sites and found the same issue but in these cases various functions simply would not work on a Mac. Fairly poor in my view that a large corporation would not have their IT staff test on both platforms.

(By Anonymous Susan956, at Sunday, July 08, 2007 5:29:00 AM)  Edit Comment

I have a MAC for almost a year now and never got used to Camino or Safari. I love Firefox especially because of Greasemonkey, which is something very wonderful for a almost total computer illiterate person like me. To your point, I had this freezing problems a couple of times but not so bad as to consider going two versions of Fox back. I hope the FF people find and fix the problem.
Another thing, once in the blogger help group someone was asking about widening the post space and so on and I suggested greasemonkey. some regular commentator there said that google does not allow greasemonkey that it is againd the TOS. Ever heard about it?

(By Blogger Márcia W., at Sunday, July 08, 2007 1:54:00 PM)  Edit Comment

Thanks for your comments Susan and Márcia W.

Susan, I don't use a Mac myself but I feel your frustration. Unfortunately many services go for the highest market share or as you Mac users might say the lowest common denominator! Mac users have fought back however, for example regarding the BBC iPlayer.

I think that as with so many things it's down to money - it costs more to build and test for compatibility with Macs than many companies think is worth it, given the relatively small userbase. It's only when the number of Mac users reaches critical mass that companies will begin to provide Mac-compatibility in earnest.

Take Firefox. It's gradually starting to eat into IE's market share, finally - at least one bank I know of recently introduced Fox compatibility. But it still took a while for that to happen. I don't know if it will become popular enough that people will start to code for both Fox and IE, but still it's much easier to produce a standard-compliant website which works in both IE and Fox than it is to develop software which works on both PC and Mac. So I fear Mac compatibility (not to mention Linux) is probably a way off.

Marcia, it's interesting to know you've had the freezing problem too. I had it a bit before but it's the extent to which it's got a lot worse recently that finally prompted me to revert.

On the TOS I've not heard that using Greasemonkey is in itself a breach of the Google TOS - it really depends on what you use it for, like any tool. Did you have in mind the debate on Greasemonkey and Gmail (see the comments) or Greasemonkey and Google Calendar? I'm not sure it's against the Blogger TOS though, I've used Greasemonkey for some time with Blogger (e.g. to enlarge the post editor) and no one's ever taken me to task for it.

While the Blogger TOS says you can't modify their service, we're not trying to are we? Just making it more accessible and usable for ourselves. That's what I'd argue anyway. I guess it depends on exactly what you use Greasemonkey for, as I said before.

(By Blogger Improbulus, at Sunday, July 08, 2007 9:10:00 PM)  Edit Comment

I can only guess google will not like the scripts that remove adds from gmail and you tube ? I like very much the script that integrates gmail with reader and absolutely love the one the removes the comments off you tube. Like you said just to enlarge the post editor is personal but avoid the adds may imply that you are just too independent for their taste?

(By Blogger Márcia W., at Monday, July 09, 2007 2:35:00 PM)  Edit Comment

I just came across a page that had many many people speaking of freezes etc they are having with One person said they had rectified a number of problems by cleaning their user profile and re-doing that. Another resolved their particular problem via the enhanced history manager.

V5 is now available and is said to have resolved two major bugs from 4. *shrug*


(By Anonymous Susan956, at Tuesday, July 10, 2007 4:27:00 AM)  Edit Comment

yes, ever since I upgraded to Firefox 2.0.0.x a week ago, I (oh well, my PC) experience the freeze and slowness-problems you describe. But I do not suffer from ice-cream cravings nor from hair-tearing attacks. So I assume that part of your description is entirely personal and subjective.

But practically: what am I to do?!? Just wait till Firefox gently prods me to install a higher version (hopefully without those problems). Or revert to a lower version, as you did. But how am I to do that? Can I use (the excruciably slow) firefox version I have now, to re-download the older version? Might that not take ages then? Or do I first have to un-install current Firefox and use other browser to install lower Firefox? (and where do I find that lower version? )

Oh and another Firefox-problem (not a new one though): it does not display the "rich text" features of hotmail - so no bold words nor cute italics nor any colours possible when using hotmail via Firefox.

(By Anonymous generalist geek, at Wednesday, July 11, 2007 12:27:00 PM)  Edit Comment

erratum for previous comment : please read in previous post "excruciably" as "excruciatingly" (i think ...)

(By Anonymous not-so-general geek, at Wednesday, July 11, 2007 3:25:00 PM)  Edit Comment

Given they do nothing..or did nothing for some time about spam and emailing them at the address they gave to deal with that proved a waste of time..I don't support Hotmail (or spamsexsellmail) :)

See one of my previous posts about where you can get FF V5. Mozilla have all the versions so head for them and advice. On my Mac, Safari is default so I probably would have erased the errant FF version and then uploaded a clean version to save cross over files etc. In the case of moving to V5 I would probably not erase but use their patches or similar to upgrade the 0.4V Then again I'm not an application 'natural' so my advice may be off base.

(By Anonymous Susan956, at Thursday, July 12, 2007 8:09:00 AM)  Edit Comment

Same problem here with intermittent, brief lockups using Ff on XP.

Thank you for doing all the troubleshooting and saving me from having to eat so much comfort ice cream!

(By Anonymous weez, at Thursday, July 12, 2007 9:55:00 PM)  Edit Comment

well, after one failed download of FF (because I had not un-installed FF .4 and had downloaded .2 to the folder "Downloaded files" - thus the FF from the "program files" came back with a vengeance) I seem to have managed to revert back to good ol' FF 1.5.12. Pheww ... it's not easy to regress... Ice-cream binge was that close!

@ Susan: well, you're right, Hotmail is a playground for everything & everyone unsavoury on the Net ... But am reluctant to abandon it, out of habit and because one can never be sure to have notified the address-change to all who count in cyberspace ....

(By Anonymous not-so-geeky generalist, at Saturday, July 14, 2007 2:20:00 PM)  Edit Comment

Márcia, on Greasemonkey I suspect it's not just independence but money! As Google's main source of profit is their ads I can imagine they won't look kindly on their removal. In practice of course, if you're running Greasemonkey on your own browser and only you know about the removals, it'll be hard for Google to find out and get you for it. Though technically you probably shouldn't do it, in many cases.

I suspect they'd target more the people who actually put out the products that remove ads etc or alter websites in ways that the site owner says allowed.

(By Blogger Improbulus, at Saturday, July 14, 2007 6:13:00 PM)  Edit Comment

Susan - yes I tried the Bon Echo version thanks, and it does work fine (but so does my - I have them in parallel). Haven't had time to flush out my profile etc, to be honest.

Generalist Geek - no, you've got it entirely wrong. It's not subjective at all. In me, Firefox induces icecream cravings and hair pulling outings. In someone else, it'll bring on attacks of watching reruns of Space 1999 (the original version). You just can't tell how it's going to affect you. It's a plot, I tell you, a plot! [That was my idea of joke. Just in case someone took that seriously. There's always one.]

I'm glad you managed to revert to 1.5 OK. Funny, I just installed on top of and it was OK. But yes if you want to try the pre-release of, the link Susan's given, that works fine for me too.

Hotmail, well I don't use it anymore myself I must admit, as Susan says the spam etc was terrible. Can you forward your Hotmail to a Gmail account, for instance?

(Oh, and there's also "execrably"? :D)

Weez - glad my post was of some help! So what did you do in the end, go up to pre-release, or down to e.g., and did it solve your problem? I should warn you my own problem started with brief intermittent lockups and then as time went on they became more frequent and less brief! I hope your system doesn't go the same way, but if it does at least you now know a few things to try. Let me know what you decide to do (and have yourself an icecream as a reward, if not comfort! Any excuse, eh?)

(By Blogger Improbulus, at Saturday, July 14, 2007 6:41:00 PM)  Edit Comment

By the way, no chocolate binge then? Or is that only for when you're truly, truly desperate? A step further down the path of unrighteousness than icecream, even?

(By Blogger Improbulus, at Saturday, July 14, 2007 6:44:00 PM)  Edit Comment

Well, I guess I'll wait for the full objective Improbulus account of the behavioral disorders (execrably) induced by FF before upgrading ...

Re Hotmail: is there a permanent forward option? And how to avoid forwarding all the (execrable) Spam too?

Re Chocolate & ice cream binge: just to have everyone drooling (execrably so) : yesterday I had a chocolate bomb = icecream + hot chocolate sauce + hot chocolate cake. And Firefox's not to blame ...

(By Anonymous Generalist Geek, at Sunday, July 15, 2007 6:13:00 PM)  Edit Comment

Improbulusandg-geek, don´t mean to intrude but you guys made remember a website I once saw in which the guy gave all sorts of tips to help the environment and stuff, but is seems his best argument was the site´s slogan: "save Earth, the only planet that contains chocolate!"

(By Blogger Márcia W., at Sunday, July 15, 2007 10:06:00 PM)  Edit Comment

GG (may I call you GG?) I am pleased to report that so far so good, Bon Echo is behaving perfectly. But I did decline the upgrade last night - nowadays I'm nervous that upgrading Fox will start the freezing behaviour again and I'm not sure I can survive yet another bout without icecream, chocolate and whipped cream!

Hotmail, ummm I haven't used it for a while, not sure to be honest.

Hey you don't need an excuse for a good chocolate bomb!

Tell me GG, do I know you? Your writing style is very familiar... and you're not exactly giving away your URL or profile.. If I don't already know you I feel I certainly ought to.

It is you isn't it? Being all mysterious?

Márcia W. - hey not an intrusion at all, and what a great quote! The FoE lot should be using that as their slogan if they're not already!

(By Blogger Improbulus, at Tuesday, July 17, 2007 9:19:00 AM)  Edit Comment

márcia w.: the ultimate earth -preservation-argument indeed

improbulus : There's this interesting post about Privacy on the net. Plenty of reasons not to blow one's cover! No way you're ever gonna prove GG is me ... :-)

(By Anonymous GG, at Tuesday, July 17, 2007 7:50:00 PM)  Edit Comment

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