Sorry, I am not familiar with Nero Backup, but Firefox is sensitive to other programs messing with Firefox data files, especially when Firefox is running. I really can't see why a backup program that is making a copy of Firefox data files would cause a problem like that, while Firefox is closed. If Firefox was open when the backups were made, who knows what got broken and why. '''Any chance that Firefox was running at the times those backups were made?''' As a note, Firefox doesn't carry compatibility information for all extensions in the Firefox user data files, it gets that information from the Addons Mozilla Org server as it needs it, or when you "Check for Updates" for extensions. That said, Roboform isn't hosted at AMO any longer so it wouldn't / shouldn't be effected in the same manner that AMO hosted extensions are. I don't know the answer, except to not have Nero Backup for the backups when Firefox is running. l recommend that you contact Nero Support to see if they have an answer for you. IMO, I think that Nero may have some fixing to do with their Backup application to be compatible with Firefox 3.6 versions. Norton was causing a similar problem with extensions compatibility back in Feb & Mar, but they were causing that problem every time their users were opening Firefox for the first time after a PC startup or a restart routine. Those clowns at Norton were deleting a key extension file, where the compatibility information in Firefox user data files is stored, when Windows was started.