hello,
have you tried uninstalling from the Add/Remove Programs tool?
then if you can do that, then you can go ahead and just install the latest version.
............................................................................................Main System Spec: Intel Quad Q9550 (OC to 3.4Ghz), Gigabyte Ga-ep45-ud3l, 4gb kingston hyperX @ 1066mhz, Corsair tx 650, Nvidia 8600GT.