First of all you need to run some malware scans, it sounds like the computer has been infected. Try running several malware scanners, you can use any of the following: * [http://www.malwarebytes.org/mbam.php Malwarebytes] * [http://www.superantispyware.com/ SUPERAntiSpyware] * [http://www.lavasoft.com/products/ad_aware_free.php Lavasoft Ad-Aware] * [http://www.microsoft.com/windows/products/winfamily/defender/default.mspx Windows Defender] (If you use Microsoft Security Essentials then you will not need to use Windows Defender) As for Firefox appearing, that implies it has not been uninstalled. The [http://kb.mozillazine.org/Uninstalling_Firefox uninstalling Firefox] article shows how to manually remove Firefox if the uninstaller failed.