Server 2003 and logon failure:…

I am running Server 03 R2 on a file server at a branch office. The computers on the network all run XP SP2. I get the error “Logon failure: The target account name is incorrect” when trying to file share. the ip address for the server works to get to network resources, but the server name does not. I think this is a replication problem, but I cannot find the specific location to fix the replication problem. I have redefined the DNS and WINS with no luck. Any other ideas?