Hi Zeppelin
I'm not on the xp machine at the moment, so I don't know if you can do this but you can on older os. Boot up in DOS mode, then in directory where os is (assuming C) type
C
scanreg/restore (yes it is a backslash followed by forward slash) You will then be presented with a list of dates when registry was ok, assuming you have a corrupted registry. Click on the date you wish registry to go back to. As I say I don't know if this function is available on xp or whether you're just stuck with system restore ?