1. See Backing up your information - Always a good idea to back up your user information first.
  2. Download the latest version of Firefox 2 from http://www.oldapps.com/firefox.htm
  3. Uninstall Firefox, if you are using the Firefox 3 uninstaller when asked say no to "Remove my Firefox personal data and customizations"
  4. Make sure that there are no files left in the installation folder, default location C:\Program Files\Mozilla Firefox
  5. Go to your profile folder.
Firefox 3 would have converted your profile to the Firefox 3 format by creating some new files. You should delete these files along with some others to avoid having problems either now or when you decide to update to Firefox 3 at a later date.
  1. Delete the following files:
    • content-prefs.sqlite
    • places.sqlite
    • downloads.sqlite
    • cookies.sqlite
    • permissions.sqlite
    • formhistory.sqlite
    • signons3.txt (if the profile folder does not contain a file called signons2.txt you can also remove key3.db)
    • urlcalssifier3.txt
    • extensions.cache
    • extensions.rdf
    • extensions.ini
    • localstore.rdf
  2. Install Firefox 2.