I've been going back to IE7 lately because FF is acting poopy and I'm not in the mood to toubleshoot it right now
Have you tried Opera? It has lots of nifty features plus tons of skins and widgets. The newest release, Opera 10, has this thing called "Turbo". It helps speed up slow internet connections by using proxy servers to compress data and image traffic before it reaches the browser. There is a bit of image distortion when you have it at full acceleration but I keep mine on automatic most of the time.
By the way, have you tried removing FF and installing a new copy?