What's your computer system and Firefox version?

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

FredMcD said

What's your computer system and Firefox version? You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article. Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Windows 10. Firefox 50.0. I tried lots of scanners none of them was able to fix the problem. I can temporarily remove that homepage but it comes back again. I look for a permanent solution which I wasn't able to find out yet inspite of all the search I've made.

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

FredMcD said

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

That's not the case. I can change homepage but it comes back again after 2 or 3 days later.

mozilla.cfg is an optional file that doesn't come with Firefox. Added by the user, a company IT admin, or installed via malware. That will reset whatever fix you do when Firefox is restarted

And with that URL added to the Firefox shortcut, my guess is malware. If you delete that URL and it comes back when Windows booted cold or even restarted, you got malware in Windows causing that.

You can use 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

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection built-in.

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

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

the-edmeister said

mozilla.cfg is an optional file that doesn't come with Firefox. Added by the user, a company IT admin, or installed via malware. That will reset whatever fix you do when Firefox is restarted And with that URL added to the Firefox shortcut, my guess is malware. If you delete that URL and it comes back when Windows booted cold or even restarted, you got malware in Windows causing that.

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You can use 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

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection built-in.

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

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

I've already tried

• MalwareBytes' Anti-Malware
• AdwCleaner
• Hitman Pro

I'm using Windows 10, meaning I've built-in Windows Defender.

None of those help me to solve that problem. I looked for suspicious softwares and adds-on and nothing seems to be problematic.