Try:

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

This can also be a problem with the file(s) that store the extensions registry.

Delete the files extensions.* (extensions.sqlite, extensions.rdf, extensions.cache, extensions.ini) and compatibility.ini in the Firefox profile folder to reset the extensions registry.
New files will be created when required.

See "Corrupt extension files":

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

If you see disabled, not compatible, extensions in "Tools > Add-ons > Extensions" then click the Tools button at the left side of the Search Bar (or click the "Find Updates" button in older Firefox versions) to do a compatibility check or see if there is an update.

Thanks for the help, but I tired what you suggested and it did not work.

Did you check all suggestion from http://kb.mozillazine.org/Preferences_not_saved like deleting or renaming the file pres.js in the Firefox Profile Folder?

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

Yes, I tried deleting the pres.js file.

Try to delete compatibility.ini in the Firefox Profile Folder.
That should initiate compatibility, but hopefully it won't return a next time.

If that doesn't work then try a new profile.

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

See Basic Troubleshooting: Make a new profile:

• https://support.mozilla.com/kb/Basic+Troubleshooting#w_8-make-a-new-profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

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

the new profile did the trick. thanks.

You're welcome

Please click the Solved It button next to the answer that solved your Firefox support issue, it appears when you are logged in, so this thread gets marked as Solved to help other users who may have this same problem.

The topic, "Create A New Profile..." helped me solve this problem and a second related one. Thanks much...

I am a Windows XP user and had firefox5 installed automatically by the auto-update system. From then on my problems started. I eventually found that the quickest, cleanest way to solve this problem was to save my bookmarks as a html file. Then FULLY uninstall firefox5 and delete the folders in C:\Program Files\Mozilla Firefox and C:\Documents and Settings\"username"\Application Data. I then did a clean, fresh installation with Firefox 5.0.1 (which is now available) and reloaded my bookmarks from the saved html file.