When I brought up my Firefox browser this morning, my bookmarks were gone, and there was an add-on toolbar at the bottom of the screen. I figured out that I had to go to View>Toolbars>Bookmarks Toolbar, and check that to get my bookmarks back, then View>Toolbars>Add-on Bar, and uncheck that to get rid of the add-on bar. When I was finished web browsing, I closed Firefox, but when I brought it back up again later, I had to repeat the process, because the bookmarks were gone again, and the add-on bar was back again. This happens every time I close and restart Firefox. It's never happened before.