Server not showing up in My Network Places

I have a 2003 server that is not showing up in my network places (MNP). At one time it did show in MNP but no longer and for no apparent reason. It is on a 2003 domain and all of the other servers are showing in MNP. I can ping it and also access it via //server_name. Here’s the strange part. If I reboot the server it appears in MNP for an hour or so then disappears. Any suggestions?