There is an easy way to reset firefox by re-installing, but do you have access to another web browser during this process, like internet explorer? because i will suggest we uninstall firefox using the add/remove programs console in the windows XP control panel, and then download a new copy of firefox using internet explorer and simply re-installing the program. This will refresh all of the files that firefox uses to operate cleanly.
oh yes, i forgot about that!
not to fear, you can still save your bookmarks
- Find your profile in c:\Documents and Settings\[your XP user name]\Application Data\Mozilla\Firefox\Profiles - There should be a subfolder there called bookmarkbackups. Find the most recent bookmarks html file in there (usually with a date after the 'bookmarks' bit.
copy that html file somewhere else like your desktop, then you can start the process of uninstalling firefox.
internet explorer "should" be able to import the file using the import/export command on the file menu.
If you cannot see the file menu, you have to right click where your tabs are and enable "menu bar"
else you can just go to mozilla.com again and download the latest copy of firefox