In Powerpoint 2010, if you do a search and the text you're searching is inside any of the Notes to your slides, it will show the Note at the bottom of the slide in a separate pane.
The annoying thing is that there's no X to close that pane once you're done with it.
The simple solution? Move the mouse pointer over the divider tipbetween the slide, so that it becomes a double headed black arrow with vertical lines - as outlined in red in the pic below.
Then click and drag that divider down to the bottom of your window with your mouse.