Error 48 on W2000 server

I have a C5.5 app installed at site using a W2000 server and W2000
workstations and am getting a persistant error 48.

The server guy has ensured that all users have read/write and create access
to the server but the problem persists.

At another site running Win98 peer to peer there is no problem,
understandably W2000 is more complex.

Does anyone have a suggestion as what might be the issue here?

Thanks in advance,
Roger Bogda