Removable slots... that is a very weird message. Whenever I see "locked" my instinct is to suggest a regular shutdown and restart of Windows. That should release file locks, complete any deferred updates, and hopefully resolve any transient permission issues. If that doesn't help: I think the program files might screwed up. Usually the best thing to do in that case is an "in place" update where you simply run the latest installer and let it freshen up the program files. You shouldn't lose any data in this process but if you want to be sure, you could back up your data using the steps in the following article: [[Back up and restore information in Firefox profiles]] And then to get the latest installer, use the link in this article: [[Custom installation of Firefox on Windows]] Any progress so far?