I've been having the same problem too with pop-up ads that I thought were from these forums (after all, they only opened up here, curiously). But after taking your guys' advice

and installing Ad-aware6 I discovered there were a bunch of nasty data miners

in my system including the culprit of these non-stop pop-ups here at AT, the 'FlashTrack' data miner :|. Others detected in the scan were IGetNet, Cydoor, EZuLa, and the infamous 'Gator'.