Are you using IE or Firefox? Personally, I use Firefox and have had much fewer problems with webpage popups and other issues since. (I also use McAfee virus software and firewall - I had Zonealarm for a long while until it gave me an error that wouldn't be resolved - and then I found many other people encountering this problem as well)
'68 Firebird, 350-4, 2 spd auto, triple black, Dlx Interior