This is a common error I hate! Here are the common causes.
A.) File and Printer sharing is disabled.
B.) The master browser is multi-homed (has more than 1 NIC) and File and Print Sharing is bound to more than one of them, or the NIC with File and Print Sharing is NOT the primary NIC.
C.) Having the NetBEUI protocol installed can cause this error.
To remedy correct one of the situations above. Enable File and Print sharing on all domain controllers, and any computer in the browse list. This error is related to NETBIOS.