OK, it is time yet again to update FireFox, so I download the update, forgetting that an update is not a patch, it is the newest version.? When I remember this, I am not in the mood to install a new version, so I simply closed the install boxes (without actually doing anything more than downloading the update), figuring that it would bug me about it later and I would install it then.? But now it won't launch, and gives me an error message stating that "The program must close to allow a previous installation attempt to complete.? Please restart."

Try this:

Fixed :-)