Inserted into the forum for the benefit of anyone else searching for help with the:

Open failed on file: ..\..\DATA\SOUND\GFSAMPLE.IFF

Message trying to play Wing Commander III.

You must use the "-t cdrom" option when mounting the D: drive to play Wing Commander 3 and presumably any other game that uses a CD-ROM. If you forget to do this, you will encounter weird error messages like the above.

Syntax:

z:\> mount d d:\ -t cdrom.