Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of. You can try these free programs to scan for malware, which work with your existing antivirus software: * [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://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. Did this fix your problems? Please report back to us!

delete your user.js file http://kb.mozillazine.org/User.js_file follow directions here https://support.mozilla.org/en-US/questions/956794

'''5d1c9gc7.default''' is your Firefox Profile folder, where your personal data and most add-ons are located.

You can rename or delete the prefs.js file and possible numbered prefs-##.js files and a possible user.js file to reset all prefs to the default value. *http://kb.mozillazine.org/Preferences_not_saved *http://kb.mozillazine.org/Resetting_preferences