Exchange Server hangs applying computer settings
I recently had a problem when I rebooted an Exchange 2003 server after some updates and it refused to display the winlogon screen. Instead it sat at "applying computer settings". I left it for around 10 minutes before realising something was seriously wrong.
Not being able to logon I was unable to diagnose the problem locally so I used the computer management console on another client to view the event log on the Exchange server. A quick look revealed a frequent error in the application log:
Event ID: 9157
Description: Microsoft Exchange System Attendant does not have sufficient rights to read Exchange configuration objects in Active Directory
The problem occurred because there are 3 security groups in Active Directory that Exchange queries in the Users Organisational Unit (OU) during startup:
Exchange Enterprise Servers
Exchange Domain Servers
As it turns out, during a recent restructure of Active Directory someone had moved the above groups into a different OU and this was the cause of Exchange hanging and recording the above entry to the event log. Moving the 3 security groups back into the Users OU almost immediately allowed Exchange to display the winlogon screen without requiring a restart.
More information is available here: