Well all I can suggest is rollback SH3commander and unistall that MultiSH3 and SH3
Start again
Removing from Vista is different
There is a Vista dedicated thread
http://www.subsim.com/radioroom/showthread.php?t=105144
Somehow something has got screwed
As I said not used MultiSH3 as never felt the need despite 8 or 9 different installs but if you say it cant be pointed to a different drive then am not really sure why SH3commander is looking there for it