Recently, a colleague encountered an interesting problem after installing Exchange 2003 sp2. The OWA gave error 503 on the sole exchange server.
Restarting the services revealed an event ID 122 for the source EXOLEDB. “Microsoft Exchange OLEDB was unable to initialize property table”.
A quick check with Microsoft Support web site revealed a tech doc but strangely the mentioned folder cannot be enumerated. Since it is talking about the public folder, I checked the public folder access in OWA. All the rest of the sites are listed but not mine!
I thought the OWA virtual server was corrupted so I bound another IP and created another HTTP server. It revealed the same error. Therefore it has to be something broke at the core.
Further search on the Internet revealed a newsgroup posting. Recreate the mail store by moving to another new mail store or run defrag. Surprisingly it worked and fixed the problem.