A corrupt profile can cause various problems with Firefox.You could create a new profile using Profile Manager.I prefer to reinstall Firefox.
Backup your Bookmarks(.json) to a folder of your choice.You will need it to restore it later.Uninstall Firefox and do not save your settings when asked.After uninstalling Firefox run CCleaner.
Install Firefox.When installing Firefox select do nothing when ask to import from IE.Restore .json backup file you saved to restore your Bookmarks.Configure all your Firefox settings.Install Add-ons and Plugins.
How to reset when using ForceField ( standalone ) or in Browser Security in Extreme :
Turn off ForceField to reset Firefox.After you reset Firefox and everything is running as it should.Close Firefox and Turn ON ForceField and Clear virtual data.
Also turn OFF ForceField for installing and updating Firefox.This is also valid for installing Add-ons and Plugins.
Hope this helps.
This is of no help. No amount of uninstalling, reinstalling is resetting FF. I disable FF. Completely uninstall Firefox, then reinstall. Open it and set it up. In the add-ons it is already showing that the FF toolbar is installed even though it does not appear anywhere. I open ZA and enable FF, still nothing. I close firefox and reopen it, the old profiles screen opens. ZA extreme is not resetting forecefield and it keeps re-using the old profiles for the previous installation of firefox. Even though in the firefox profile screen I deleted all the profiles, still FF is not accepting to install on the new firefox installation and keep bringing up the old profiles screen which is now empty but still runs firefox and shows the FF toolbar.
How to manually delete all the old configuration files made by ForceField?