Answers: try~
go off line delete firefox from add and remove.
if you are on line firefox is live.
if this doe's not work.
go to search and type in firefox/mozilla
this will bring any duplicate programs up delete them.go on line and reinstall.
you may not know but even if you do not like or use it quite a few programs use IE to auto download,
microsoft updates do+others
hope this helps
If you have XP uninstall it then go to Start, My Computer, Local Disk, Program Files, find firefox. Delete the firefox folder and then go to IE and redownload it. That should work. It it does not its Windows. You need to reinstall windows or contact a computer trouble shooter. Do NOT go to bestbuy or some retail store like that. They will crap your PC up.
press "control alt del" and go task manager, click on processes and find "firefox" in the list. right click on it and press "end process" it might ask are you sure, .. click yes
now try and open firefox again