Have you tried downloading the product? Just kidding.
You have some bad malware. Well actually pretty well designed malware. It doesn't matter what scanner you use, its not going to find it.
The malware detects when your browsing the internet, and displays the popup message then so that it seems real. As soon as you boot its loading itself and hiding itself so that spyware scanners cant find it.
Boot into safe mode, (which loads only system critical processes), and run a scan then. For good measure I would run at least 2 different scanners, 3 if you wanna be real safe. That should take care of it. Also while in safe mode go into 'start > run > msconfig' and click the 'Startup' tab. Google any processes you don't recognize and turn off any that shouldn't be on or you don't want on. Restart the computer and voila. Happy New Year.