I found a quick way to fix this which allows you to get back your bookmarks and history but NOT the password. By the way, if you have got the problem, FireFox doesnt let your restore your backups of your bookmarks, it says they are corrupted even though they are not. Anyways, here is the guide:
- Navigate to /My Computer/Documents and Settings/USERNAME/Application Data/Mozilla/ and backup that folder to your My Documents.
- Go to the control panel and then add/remove programs and uninstall FireFox. Make sure you tick the box that says delete all personal data, bookmarks, saved passwords etc.
- Download FireFox again from HERE and install.
- If everything has gone ok, firefox should be normal again with the default bookmarks etc.
- Go to the menu BookMarks and select ‘Organize Bookmarks’.
- Click on import/backup bookmarks, restore and then choose file…
- Navigate to the backup of the Mozilla folder we backed up earlier and go to Mozilla/FireFox/Profiles/*******.default/bookmarkbackups/ and click on the newest one.
You should now have all your bookmarks and history back. As I said, you do NOT get your saved passwords back put you can just enter then again.