If you are getting lots of pop-ups, it is possible your PC is infected with a virus or 'spyware'. Are you running any anti-virus software, or anti-spyware?
(I use AVG from
http://free.grisoft.com/freeweb.php for anti-virus, and Spybot Search and Destroy from
http://www.spybot.info/en/download/index.html for anti-spyware (both free to home users).
[Edit] beaten to it, I see.