The other day, my system crashed and screwed up Firefox (lost bookmarks).  I fixed that.  Thursday morning Firefox crashed again and wouldn't restart (said that it was already running but not responding).  I've since then rebooted several times, uninstalled, re-installed, deleted manually, and restarted again...and it's still saying that there is an instance of Firefox running that's not responding.  WTF?  I'm using Mozilla in the interim, but I really loved Firefox.  I don't wanna format just to get that working again, so any help would be appreciated.