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

Delete a possible user.js file and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release. You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Preferences_not_saved

Rename (or delete) the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox profile folder.

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Multiple_profile_files_created

Note that deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost.

COR-EL Thanks for the quick response. the user.js file was the culprit, I deleted the command that caused the problem in the file. Aparently some over eager program helped us. My wife will be happier at the computer.

Problem solved.