I fixed this by restarting the DNS service.
Several of my SBS 2003 servers were reporting this and also Event ID 3024 with "IP-based AUTD failed to initialize. Error code: [0x80004005]" in the description. Research pointed me to "Some Services May Fail to Start or May Not Work Properly After Installing MS08-037" which helped me to resolve this problem. See also ME956189
In my case updates were installed and somehow the DNS process ID was using UDP port 2883. After restarting DNS, the port returned to the w3wp service. You can check this by running netstat -ano|more, looking for UDP 0.0.0.0:2883 and cross-reference the PID in the Task Manager.
This error occurs because monitoring is disabled in Exchange 2003. Go to the properties of the server object in ESM -> tab Monitoring -> uncheck the box "Disable all monitoring of this server". Restart the Exchange services and observe that the server object under "Tools-Monitoring And Status-Status” changes from "IN MAINTENANCE MODE" to "AVAILABLE".