Yes, Well I’m running a Windows NT PDC, a Windows 2000 BDC/exchange server, and Windows 2000 workstations. When a workstation on the Server's Domain tries to communicate with the PDC everything is great. However, when the workstation try to communicate with the BDC it errors out. This is the result of any application i.e. Server Manager, outlook or even trying to get in to the server. The server communicates perfectly fine. And all NT workstations with accounts on the trusted domains can access the BDC fine. Event viewer displays no obvious errors. This set up has worked fine for over 6 months. This error just came up with no apparent cause.