In my 'User's Guide and Reference for Microsoft Windows' (SH35-0125-02)
on page 93 (Selecting drives within Chapter 4) I read:
   "ADSM client does not allow drive aliases created with the DOS SUBST
   command to be backed up. In addition, since the aliases drive has the
   same volume label as the physical drive it aliases, the client is not
   able to back up the physical drive. Drive aliases created with SUBSt
   should be deleted prior to starting Windows."

...and now the discussion may start...

Pieter Groen