On my Win 7 system, I have mapped 4 drives to a XP system using the "net use" command. They are mapped correctly as p,q,s,t on the Windows 7 system. They show up in the "Power Desk" app which is a file manager utility program. The mapped drives work correctly in that program.
However, they don't show up in explorer on the windows 7 system. All other drives are shown, but not the mapped drives. Also, if I bring up the file open dialog box from an app like notepad, they don't show up either.
On another Win 7 system, I can map the drives exactly the same way and they do show up in explorer. It must be a setting that is different on the Win 7 system that does not work.