Scan for malware with all programs * [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] [http://windows.microsoft.com/MSE Microsoft Security Essentials] is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one. Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article.

EDIT: It's definately a virus - you must remove it before proceeding. Try the following: 1) Go to '''about:config''' (type it in the adress bar). 2) Enter. 3) Search for '''browser.startup.homepage'''. 4) This variable controls what page is loaded when you start Firefox. If its value is '''v9.com''', change this value to the website you'd like to load on startup and it should be fixed.