I can't reproduce it, try [[safe mode]].

Do a malware check with a few malware scan programs.<br /> You need to use all programs because each detects different malware.<br /> Make sure that you update each program to get the latest version of the database before doing a scan. * http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware * http://www.superantispyware.com/ - SuperAntispyware * http://www.safer-networking.org/en/index.html - Spybot Search & Destroy * http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free * http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page See also "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked and [[Searches are redirected to another site]] If you can't fix it with the above listed scanners then you need to ask advise on one of the forums that specialize in malware removal mentioned in the <i>Popups_not_blocked</i> article.

install a siteblock Add-on I think it is a bug in firefox. Mozilla has to come up with an upgrade which will prevent these type of attacks.