Workgroup failure

This is a problem I have seen posted several places around the internet. Several WinXP (Home) SP2 machines in a small office environment connected via switch to a DSL modem/router. Straightforward little network with DHCP being provided by the router. The XP machines will not stay bound to the workgroup. If I try to browse the workgroup through My Network Places I get the following confounded error message:

is not accessible. You might not have permission to use this network resource. Contact the administrator (that would be me!) of this server to find out if you have access permissions. The list of servers for this workgroup is not currently available.

Now remember, this is strictly a peer to peer network. No server, other than the aforementioned DHCP router. No Local or Domain Security Policies in force. Nada. I am pulling my hair out over this one. I hate being stumped. I have disabled the Firewall through the Control Panel applet. I have disable the Firewal and Internet Connection Sharing Service through Services applet.

What am I missing? Your comments admonishments and suggestions are welcome.

Eansor