I think the problem is related to 3 areas:
1. Computers configured for different Workgroup and Domains
2. Browse master issues with Workgroup, Domain and Domain Controllers
3. Mulitiple login accounts for a user on different domains.
I have listed Microsoft Reference Articles that I believe are related to your problem. Refer to Q100011, Q140390, Q117633, Q131096, Q102878What really stands out is MS Article Q100011
User Name Duplication
There should not be user name duplicates on different domains. If a user name is duplicated across different domains, there will be inconsistent results when a logon is attempted from a Windows for Workgroups workstation on that Windows NT network.
