It sounds like your computer may be infected with some sort of a virus / Malware. I suggest the following resources: [[Is my Firefox problem a result of malware |Is my Firefox problem a Result of Malware]] is a Mozilla Support article with some good tips on avoiding and fighting malware. To double check your system is clean, do the following (Not official Mozilla advice, just good practice from personal experience) Download and Install MalwareBytes Anti-Malware, run a full Scan. [http://www.malwarebytes.org/ http://www.malwarebytes.org/] Download and Run TDSSKiller [http://support.kaspersky.com/faq/?qid=208283363 http://support.kaspersky.com/faq/?qid=208283363] Download and Install Microsoft Security Essentials [http://windows.microsoft.com/en-US/windows/products/security-essentials http://windows.microsoft.com/en-US/windows/products/security-essentials] (not an official endorsement, but I personally recommend MSE as an awesome permanent anti-virus) Also, click "start" then Control Panel, the "Programs and Features". Find anything related to PCTools, and uninstall it. Double check for all Windows Updates. If you are still having problems with Malware after that, I would recommend either [http://www.bleepingcomputer.com/virus-removal/ http://www.bleepingcomputer.com/virus-removal/], or having your computer cleaned by a professional. Also, you should begin to prepare to upgrade to Firefox 11. Firefox 3.6 will be dropped from support in a few weeks, which means it will no longer be receiving security or stability updates. Firefox 11 is up to 7 times faster than 3.6, has lots of new features and improvements, as well as support for new web standards and security features. [http://www.mozilla.org/en-US/firefox/features/ http://www.mozilla.org/en-US/firefox/features/] and [[Updating Firefox|Updating Firefox]] have more information.