Oh, and so you don't get it again, do not, when surfing certain porn sites, agree to download any kind of "special viewer that's needed to view these great XXX clips..."
Don't be embarrassed. It's happened to the best of us.
Bottom line on surfing porn videos...if it won't play automatically in Windows Media Player or via Flash Video (as in Redtube.com etc) then DO NOT try and run the videos.