Its my first time working on NT4 [started my career on Windows 2000]. I have configured a BDC in NT4 environment. The server is identified as BDC and directory has successfully been rplicated. NLTEST reports the BDC as Backp Domain Controller and sucesfful replication. But as soon as it starts up [or connected to the network] the users start getting the authentication failure stating "No domain controller is avaiable or can not be contacted ....". When i shut down/dissconnect the BDC, the problem goes off. Anyone to help me out.