You didn't mention WINS. You'll need a WINS server for the W9X clients. Your symptom indicates a WINS problem of some sort. Do you have more than one WINS server?
Make sure the clients in the remote office are configured to point at the DC for DNS and WINS. Check the WINS database to make sure the clients are registering.
If you ping the fully qualified DNS name of the DC, does that succeed?
If so, you know you have a WINS issue and not a DNS issue. You can add a
Domain name to the DNS Configuration of the TCP/IP stack and that might
resolve your problem, as well. But you'll still need WINS for NetBIOS
This was first published in September 2001