Tricky RAS issue in NT4/2000 Mixed Domain

[Bullnuts]

I have recently replaced a NT4 BDC that was serving as a RAS server with a New W2K Server set up as a stand alone server running RAS joined to the NT4 Domain. The Network has 1 NT4 PDC 3 NT4 BDC's and 3 W2k Servers Member Servers. We are not using any active directory. The New W2K Server RAS is all configured and I can dial in establish a connection(auth. ms chap v2) and Ping and tracert to all servers by name or IP. I HOWEVER can only map Drives to other W2K servers. I cannot map drives to NT 4 Servers, I get a standard windows message saying "an error occured while reconnecting g: to \\servername\share microsoft windows network. The local device name is already in use. The connection has not been restored." It is also logging at the workstation under event viewer/system Source MRxSmb Event ID 3019 "the redirector failed to determine the connection type"
Could this be a problem in RAS config or a NFS or NTLM version issue. Any help or direction would be appreciated.
Thanks
Stephen