See Pop-up blocker settings, exceptions and troubleshooting for possible causes.

One possible cause is malware, try running several malware scanners. It is best to run several as each will pick up things that the others miss. Some scanners you can try are:

• Malwarebytes
• SUPERAntiSpyware
• Ad-Aware
• Windows Defender
• Spybot S&D

I have Norton anti-virus installed on my PC. I'm afraid installing a new malware programme will conflict with my anti-virus and cause my pc to probably crash.

Try the first 3 and the last one, you can install them and run them to scan for any malware. If you find any option to make them resident or run at startup, just do not select the option. If you wish you can uninstall them after performing the scan.

Fresh install win xp mce 2k5 win updates are current fresh firefox install 8.0

avast! and glary utilities installed before setting foot on the net.

popups right out of the gate with block checked.

scanned, no virus or malware even with adaware.

pointing toward a browser issue instead of malware.