I experienced this problem today, drive C: of my local computer "Pegasus" was not appearing on the remote computer as "C on PEGASUS" when I connected to the remote computer via Remote Desktop (Terminal Services.) All other drives of Pegasus were showing fine on the remote computer, but the one I actually needed (C:) was not. The drive did not even appear under "\\tsclient" in "Network Places".
Judging by the problems reported by people from all over the world who have this problem and are searching for solutions on the interwebz, it may happen with any local resource, like printers, the clipboard, etc.
Luckily, I found a solution to the problem:
Terminate the RDP session not by closing the RDP window, but by actually logging off. Then, start a new RDP session, and the problem will have most likely gone away.
It is unclear why local resources sometimes fail to show on the remote computer during an RDP session; it is one of those things that "just happen", and that tend to go away if you just "close and reopen it". (Or get out of the car and get back in again, as the joke goes.) The reason for the frustration with this particular problem is that more often than not we do not really "close and reopen it", because we tend to just close the RDP window, which does not terminate our logon session with the server. By logging off and connecting again, the logon session gets restarted, and that's the "close and reopen" needed to fix the problem.
