Spyware Issue

I have this nasty Firefox spyware that opens pop-under ads in IE.  If I just browse in IE, no pop-under.  It only happens in Firefox.  I have both Spybot and Ad-Aware, but neither are picking this thing up.  Sugguestions?  Anyone having similar issues?  Has anyone walked a mile in my shoes and conquered this demon!?  HALP!?

Also, I have the official 4Chan Firefox extension.  Could this be what's causing the trouble?

Thanks, guys.

>>3
xbox360 would be a really awesome console if it didnt have so many fuckin shitty faulty errors. my friend had to send his xbox 3 times already to fix it. so for now xbox360 is a heap of shit.
no opinion on ps3 or wii for now