Assuming you are running Windows 98, restart the computer fresh, then when you are at the desktop again, hit Ctrl-Alt-Del and look at the list of running programs. Go ahead and end task to every one listed there except Explorer and Systray. Once you do that, load up the Beta 11 upgrade file and try it again. If this works, then something is starting up with you computer that is capturing that com port. Most PDA software will do this.

I really need to get a new job outside tech support :-)