Ad-Aware 2008 is a pretty good program, I use it...I also have AVG and Spybot, and to top it all off my dad has a license for PrevX...which is a pretty powerful anti-virus program. My computer is practically invincible. lol
Anyways you can try PrevX's 30 day trial and see if that will help, the homepage is here. I'm hoping this will take care of your problem, I'm pretty sure it will too, PrevX is awesome...though you will need to pay after the trial.