Which browser and OS are you using? Install Google Toolbar to block popups.
If you get Popups even after installing Google Toolbar, download HijackThis and unzip it to dedicated folder (like C:\HijackThisFolder\hijackthis.exe).
Run it and click the button "Do a System scan and save log file". Copy the entire contents of the log file and post it.
scrub your pc with ms antispyware, spybot, spywaredoctor.
install google toolbar. its got one of the best pop-up blockers. yahoo is also good !
if you r comfortable with IE, no need to change your browser. but try to install MAXTHON, an IE based browser. it too has got a great pop-up and ad-blocker !