Remote Desktop does not always work correctly (my experience).
One of problems is with a Cold Start of the Router. Example: If the Wireless Laptop is on top of the ARP stack and the rest (hardwired PC's) are on the bottom, then at (cold) re-start the ARP stack could be cleared and the hardwired ones will have a new Internal IP-address, while the Wireless ones will fall on the bottom, throwing the IPs of the Remote Desktop out of whack.
One way of dealing with that is to assign a Static IP to the PC's, but that defeats the whole purpose.
As Soybean says: The proper way of dealing with this problem is to "enable Filesharing".
By the way: Remote Desktop does not work anyways for Windows 2000 and below.