Last month we had a functioning NT4 domain with a PDC and BDC. Additionally, I have an Exchange 5.5 box on NT4. A virus got through some back door (now plugged) and screwed up a database, etc., on the PDC. We planned a near-future upgrade to 2000 AD anyway but this situation caused us to go ahead and implement the 2000 upgrade. The hardware was already available so we installed 2000 and got everything up and going. The original NT domain was XYZ.com. Since we kept the Exchange 5.5 (NT4) box, we tried to join it to the 2000 domain called XYZ. Obviously, there was a problem with user accounts so we promoted the BDC to a PDC in the XYZ.com domain to authenticate logins for the Exchange machine and set a 2-way trust between domains XYZ and XYZ.com. This works OK but we want to do away with the now PDC and have the Exchange box work with the XYZ 2000 domain. Any suggestions will be appreciated.