Lost Mapping Drive

I am on a 2 computer network both using Windows XP. I have been successfully mapping some files for many months. Suddenly I can no longer map. Under Network drives it says Disconnected Network Drive. When I click on this I get the Message:
"Microsoft Windows Network not enough server storage is available to process the command this connection has not been restored." The server C drive has 173 Gig of free space. Any ideas. I'm new to this Thanks