Windows 2003 SP2 compatibility issue with Exchange 2003 cluster
So you went ahead and installed Windows Server 2003 Service Pack 2 on your Exchange 2003 cluster because it’s a “good thing” (Not that service packs are not good things, they really are!).
Everything went well until all of a sudden, your users report that they can’t access their mailboxes through OWA. They complain that they get the dreaded “500 – Internal Server Error” message in their browsers.
Its time to dig into the Microsoft Knowledge base. KB article 841560 suggests that you install Exchange Server 2003 Service Pack 1 on your cluster and install hotfix 841561.
And then… you should find your problems melting away.
Shijaz Abdulla is a Partner Technology Advisor at Microsoft, helping their top tier partners build on their Microsoft practice. He is also a trusted advisor to medium enterprise customers in Qatar. He is a blogger, tech enthusiast, and a Microsoft evangelist.