problems with mozilla firefox

so far I cant find much help anywhere else and you guys are the best that I've found, well I'm having problems uninstalling firefox everytime I try to uninstall it tell me that "Your computer must be restarted to complete a previous upgrade. do you want to reboot now?" and I've rebooted 100 times and still nothing happens... then I've tried installing over it and it tells me that the version is not compatible with my system and need to install one that is compatible with 64bit version, but I've looked on the mozilla website and can't find anything like that.... I currently am running windows 7 and my spyware and antivirus is mcafee and nothing shows up.... Please guys if theres anything you guys can do to help out that would be great!