Hello,

The tags on this question show that you are using Firefox v26. This is the latest version.

You can find instructions on how to Reset Firefox here:

Refresh Firefox - reset add-ons and settings

Please note that if your PC has become infected with adware that is hijacking your browser default search provider, home page etc then you may find that the Firefox settings get re-hijacked even after you have done the reset.

You need to make sure that the adware that is hijacking the browser is removed from the computer before you do the reset.

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

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner

I've had particular success with MalwareBytes and Hitman Pro.

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

I hope this helps. Let me know if not.

Note that your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there. you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

You can rename or delete the prefs.js file and possible numbered prefs-##.js and user.js files to reset all prefs to the default value.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

Many thanks. This advice covered 'all bases' and seems to be working.

Great! Glad to hear it worked. Thanks for using Firefox.