Firefox has a pop-up blocker built in: check Tools > Options > Content.

However, popups can come from other sources, particularly external programs. To rule out the possibility of malware or spyware, try these scanners if you can access them:

HouseCall : http://housecall.trendmicro.com/

Malwarebytes Anti-malware : http://www.malwarebytes.org/mbam.php

SUPERAntiSpyware : http://www.superantispyware.com/

Also, disable any nonessential add-ons under Tools > Add-ons (especially Themes and Extensions).

Your plugins list shows outdated plugin(s) with known security and stability risks.

1. Adobe Acrobat Plug-In Version 5.10 for Netscape
2. Shockwave Flash 10.0 r45
3. Java Plug-in 1.6.0_03 for Netscape Navigator (DLL Helper)

Update the Java plugin to the latest version.

• http://java.sun.com/javase/downloads/index.jsp (Java Platform: Download JRE)

Update the Flash plugin to the latest version.

• http://www.adobe.com/software/flash/about/