My bookmarks have all disappeared, and Firefox won't allow me to add new bookmarks either. I recently updated from 3.6.9 to 3.6.10, but the problem only showed up a day later. If I try to restore, it just says, "Firefox unable to process the backup file." I've tried all the suggestions on the help site, and none of those have worked (I don't have the add-on that causes bookmarks to disappear, I haven't updated from Firefox 3.5 or less, and I don't think Firefox has created a new profile). Also: when I start up Firefox, it says, underneath the toolbar, "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem." However, I don't have any security software installed. I'm running a Mac.