never heard of that problem. try to completely remove firefox.
1. Go to Control Panel>Add/Remove Programs in XP or Control Panel>Programs & Features in Vista, and if a 'Mozilla Firefox' entry (or similar) exists, select it and click Change/Remove and uninstall it. Reboot if required.
2. Go to your Documents and Settings\[username]\Application Data\Mozilla directory in XP,
Note that this will delete all of your bookmarks and saved settings. If you want to save your bookmarks, click on bookmarks organized bookmarks, then export.
3. Go to your \Program Files\Mozilla Firefox\ directory and delete it and all of its contents.
One other thing you can try since it sounds like you are running firefox without addons. is to go ahead and download/install firefox 3
the truth is a three edged sword - your truth, my truth and the real truth.