Hi, you can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• Hitman Pro
• ESET Online Scanner

Note that not all removal programs will detect all malware, so you may need to run several or all of them.

After removal you may need to reset your home page and search, which you can do by running the add-on SearchReset.

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one. Windows 8 has antivirus built-in already.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us! Thank you.

The name of the malware is 'mysite123' & it keeps oncoming back as the default search engine after removing it thru the add on search. I ran AVG 2 times, one in safe mode but was not detected. I manually deleted it from AppData/Roaming/Mozilla then emptied the recycle bin, still it can't be removed. I ran Eset Online Scanner as recommended by Scribe, it was not detected too. But while the Online Scanner was running, AVG was able to detect it in the Temp folder, clicking the disallow button cleaned & placed it in the virus vault. Alas, mysite123 is still back as the default search engine!

Help!

Did you miss seeing this? Note that not all removal programs will detect all malware, so you may need to run several or all of them.

AVG isn't effective at detecting or removing Malware, which is why it wasn't listed by Scribe. One down, 5 more anti-malware applications to run to complete the job.