I have foxmarks installed so my bookmarks were already saved. I took note of the other extensions installed then completely removed (purged) firefox and then in my home directory (~) remove the .mozilla folder and all of it's contents by typing...
rm -rf .mozilla
...in a terminal window.
Installed Firefox 3, and ran it. At this point, it recreated the .mozilla directory, and I added foxmarks and several other extensions that I'd had, restarted and now here I am.
Regardless of what happened, Firefox is fixed and faster than ever!
Ciao!
Bookmarks