Ever since I was on FF version prior to v18.104.22.168 (and now on it), I've been seeing strange problems with Firefox (on Windows XP SP2). CPU utilization shoots to 100% quite frequently for no apparent reason (while doing plain scrolling, opening new tab, etc). FF freezes and fails to respond for a brief period during such times. I've got so sick of it that I've almost effectively migrated to (gasp!) Internet Explorer. My only "consolation" is that I'm using the "savior" Yahoo! Toolbar for tabbed browsing.
Don't think the FF problem is related to virus/trojans, however, who knows ?!!! Need to run a full scan on my machine. Probably now is as good a time as any else.
Lemme know if you've heard/come-across this and/or know of a solution to the problem (other than migrating to IE, Opera, ...) :)