A Windows program expected to see a D: and an O: drive and the program was running on a virtual machine.
My first thought was to get the system admin to create 2 virtual drives on my VM machine but then I remembered from my MSDOS days the "subst" command.
Subst associates a path with a drive letter.
I had a problem that the subst command wouldn't associate drive d: because the virtual CDROM was assigned to that drive.