One of the great things about Firefox is that it's usually easy to fix any problems that occur. You simply need to reinstall the program. (You don't need to uninstall it first and you won't lose any bookmarks or personal settings).
your getting lots of pages opening because i suspect your continuously clicking on the firefox tab to open NOT giving it time to load up in the first place if you click it 6 times you will get eventually six home pages opening ,be patient with it give it around 15 secs the first time you click on it