Comment 2 for bug 452363

I can confirm this behavior, but it goes further than this I believe. Ubufox seems to corrupt the firefox toolbars, causing items to disappear. I customize my toolbars by moving my bookmarks into the menu bar and adding buttons onto my address toolbar and menu bars. I find that ubufox eventually causes these buttons to go away, or at least go off the screen and it also corrupts the google toolbar by making most of the toolbar disappear (including the search box).

This is not knew to karmic, this has been the behavior since at least jaunty, but I think I saw it in Intrepid too.

My "fix" is to disable the ubufox extension.