If there is an icon in the taskbar thats directing you here you have installed something possibly the program that it directing you. I personally would run ccleaner
CCleaner - Home to clean all temp files Then download and install and run spybot
The home of Spybot-S&D! . Once all these are done goto start run if xp if vista click windows key and r at same time and type msconfig.Stop everything from this list except antivirus .
Then open a web browser and click manage add ons/enable and disable. Stop anything that looks dodgy there including toolbars and browser helper objects.Then go to control panel add remove programs in xp or programs and features in vista .Uninstall any dodgy looking antispyware program that relates to the pop ups your getting . Reboot PC. Download and install Avast free home edition
avast! antivirus - high security and protection from malware with anti-spyware and anti-rootkit software built in when offered schedule boot time scan select yes and reboot . Allow the virus scan to check during boot. Once finished uninstall avast and continue to use what you have now. Run ccleaner again to clean up registry .That should have given your machine a good clean up. If your problem persists we can investigate further
C:\PROGRA~1\PANICW~1\POP-UP~1\PSFree.exe what is this program?
O4 - HKCU\..\Run: [PopUpStopperFreeEdition] "C:\PROGRA~1\PANICW~1\POP-UP~1\PSFree.exe" always worried about free programs I do not recognise