Did you see this article? [[Pop-up blocker settings, exceptions and troubleshooting]] Look under the ''Pop-ups not being blocked'' section.

P.S. Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of. You can try these free programs to scan for malware, which work with your existing antivirus software: * [http://www.microsoft.com/security/scanner/default.aspx Microsoft Safety Scanner] * [http://www.malwarebytes.org/products/malwarebytes_free/ MalwareBytes' Anti-Malware] * [http://support.kaspersky.com/faq/?qid=208283363 TDSSKiller - AntiRootkit Utility] * [http://www.surfright.nl/en/hitmanpro/ Hitman Pro] * [http://www.eset.com/us/online-scanner/ ESET Online Scanner] Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article.

Also, disable the TubeSaver extension here: orange Firefox button (or Tools menu) > Add-ons > Extensions category You may need to exit and restart Firefox before that change takes effect.

You should also remove HKCU\Software\Mozilla\Firefox\Extensions [[email protected]] and other [http://blog.qisupport.com/remove-ads-tubesaver-stop-tubesaver-ads-popping-2/ registry entries ]so that TubeSaver extension can be removed rather than disabled.