the problem may be that the newer version does not find your dvd drive because it does not support that drive ,this does happen with a lot of hardware newer version do not support the older hardware.as you have windows millenium then you could just use system restore to a point just before installing the newer version and it should put you back to your older version as sometimes when you try to go backwards then you have problems with (a newer version is already on your system messages)even after they have been uninstalled.