Can u try that in the safe mode? press F8 during BIOS start up.
Yeah there's no advanced uninstall in the program that came with the game. The only options you have are Play, Install (which is grayed out because it's already installed and uninstall. And when you click that you get the error.
Tried turning off UAC and no go :-( same error. Trying it in safemode now. One sec.