Firefox’s “Back” Button Greyed Out, Bookmarks Disappear, Menu Greyed Out

Operating System: Windows XP/Vista 32bit
Firefox Version: 3.5.5
Press ctrl-alt-delete and bring up the task manager. Click on the “Processes” tab. See if you have more then one firefox.exe running. End all the process name firefox.exe. Try starting firefox again.

Update:

The cause of this problem originated from AVG marking one of the .sqlite as infected.  In my opinion if the file is infected and cannot be healed, you need to completely remove firefox and reinstall.

Windows XP: Uninstall Firefox Completely

1. Click on “Start”
2. Click on “Control Panel”
3. Click on “Add and Remove Programs” (If you don’t see this, on the left side of screen click on “category view“)
4. Choose “Mozilla Firefox” from the list of programs.
5. Click “Change/Remove”
6. The Firefox uninstall wizard will pop up, when you get to the dialog box that ask you to remove “remove my Firefox personal data and customizations” check the box.
7. Finish the uninstall wizard.
8. Open “My Computer” and naviage to “C:\Program Files\” and delete the directory called “Mozilla Firefox”.
9. Also Delete these two directories
   • C:\Documents and Settings\[Username]\Application Data\Mozilla
   • C:\Documents and Settings\[Username]\Local Settings\Application Data\Mozilla

Windows Vista: Uninstall Firefox Completely

1. Click on “Start”
2. Click on “Control Panel”
3. Click on “Programs & Features” (If you don’t see this, on the left side of screen click on “classic view“)
4. Choose “Mozilla Firefox” from the list of programs.
5. Click “uninstall”
6. The Firefox uninstall wizard will pop up, when you get to the dialog box that ask you to remove “remove my Firefox personal data and customizations” check the box.
7. Finish the uninstall wizard.
8. Open “My Computer” and naviage to “C:\Program Files\” and delete the directory called “Mozilla Firefox”.
9. Also Delete these two directories
   • C:\[Username]\Application Data\Mozilla
   • C:\[Username]\Local Settings\Application Data\Mozilla