http://kb.mozillazine.org/Preferences_not_saved

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

My current profile folder was filled with *hundreds* of "prefs-<n>.js" files! I restored a backup, and so far everything seems to work. prefs.js was NOT r/o.

rant: I am really sick and tired of getting corrupted profiles in FF! I've lost count of the # of times this has happened, usually after an upgrade. Each time I have to restore an old version, I lose hours of work on various prefs changes that are hard to reproduce. A profile repair tool is badly needed, or more work on prevention. /rant

That said, I still prefer FF to the alternatives! Thanks for your help.

You usually only get numbered files like pref-##.js if there is other software that lock the main pref.js file, so Firefox can't rename the numbered temp file with the number to replace the main file.

You will have to check the settings in your security software and make sure to exclude the Firefox profile folder.

It looks like the last time I had to restore a profile backup, the folder permissions were incorrect. Once I fixed the perms., I was able to use my current profile. I deleted all the numbered files.

Thanks.