Background: Windows 2000 SP4; Exchange 2000 V 6.0 Build 6249.4 SP3; DC; SMSMSE 22.214.171.1243. We lost power a few minutes ago and discovered the hard way a UPS was bad. As a result the Exchange server went down. After restart the server seems fine and is receiving email but no domain users can authenticate to the Exchange server. This machine is a DC. Additionally a domain admin account I usually use to manage the Exchange server is Event ID 529 (bad username or password). I can login with another domain admin account just fine. All the domain user accounts are denied with EventID 529. Ideas?