The [https://addons.mozilla.org/en-US/firefox/addon/3145/ BlockSite] add-on should be able to do that. As you keep on getting referred to a malicious site, I recommend running some malware scanners to ensure there is not a malware problem on your computer. It is best to run several as each will pick up things that the others miss. Some scanners you can try are: * [http://www.malwarebytes.org/mbam.php Malwarebytes] * [http://www.superantispyware.com/ SUPERAntiSpyware] * [http://www.lavasoft.com/products/ad_aware_free.php Ad-Aware] * [http://www.microsoft.com/windows/products/winfamily/defender/default.mspx Windows Defender] * [http://www.safer-networking.org/en/home/index.html Spybot S&D]