It shouldn't be necessary to reboot the computer to update Firefox. That will only happen if files are in use by other software and thus makes it impossible for the updater to replace them. So you need to check your security software and make sure that it isn't locking files in the Firefox program folder.

Do a clean reinstall and download a fresh Firefox copy from http://www.mozilla.com/firefox/all.html and save the file to the desktop.

Uninstall your current Firefox version and remove the Firefox program folder before installing that copy of the Firefox installer.
Don't remove personal data when uninstalling.

It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.

You can skip the step to create a new profile, that is not necessary for this issue.

See http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

I couldn't uninstall from control panel, but I was able to delete a majority of program files to where I could reinstall and now Firefox is running again, but I am having a new problem. When going in to hotmail I can get into my inbox but can't open any of the messages. Had this problem before with another update and I updated java. I did that and still not working...