Comment 4 for bug 428703

This happens in both firefox-3.0 and firefox-3.5 for me, and it happens on both the URL bar and the address bar. And it is triggered not only by the screensaver, but also by the lock screen or by resuming from standby. The problem can be "fixed" by opening a new window (Ctrl+n) and then closing it.

There is a thread started about this bug here: http://ubuntuforums.org/showthread.php?t=1261872 - as I said, "I have a theory - I think the bar highlights when normally the suggestion box would drop down - for example, when you start typing something, normally the location bar shows elements from your history that match what you're typing, or the same thing happens in the Google bar and normally it would show search suggestions. But when this bug occurs, if you type something so odd that no results would happen (and the drop-down would not normally appear), then the bug doesn't happen."

Let me know if there's any more info I can give or any log files I can attach to help fix the problem.