Hi can you follow the instructions below to fix this error, you need to run sfc /scannow

• http://support.microsoft.com/kb/929833

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 may want to 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 involved preferences can only be changed temporarily for the current session.

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