In a mixed Microsoft Exchange Server 2007 and Microsoft Exchange Server 2003 environment, an Exchange Server 2007 Client Access Server (CAS) server handles the proxy requests for Exchange Server 2003 servers. After you upgrade an Exchange Server 2007 CAS server to Exchange Server 2007 Service Pack (SP2), you may frequently receive the following event in the Application log on the Exchange Server 2007 CAS server:
This problem occurs when the following condition is true:
- The Exchange Server 2007 CAS server is located in a different site from the Exchange Server 2003 servers.
Although there is no other obvious problem, Event ID: 4999 may alert users about the W3Wp.exe process that crashes.