XP loses connection on W2K LAN

I have a W2K LAN. There is about 60 machines connected to the DC, most of these machines are either 2000 or XP and work fine. I have one machine that loses its ability to connect to shared files and folders on the local domain controller. We have WAN with are office in CA, we are in WV, it is able to access files on the servers in CA. The user logs on fine for no reason if she is working on the machine or not the connection disappears and she is prompted for a password when she tries to connect to anything on the LAN.