Sounds like Scammed, but you could be infected. Open your task list and compare the running programs in there to www.answersthatwork.com (click tasklist). Some trojans run hidden, but most things should be in there.
You also shouldn't be getting popups with Firefox which suggests you may have a pest. My FR homepage may have some information and links that could be of use to you.
Thanks. I looked and everything seems kosher. The pop unders are suspicious but I'll keep scanning and see what happens.
I bookmarked your homepage. Very helpful. You're a sport