On a server that is running Microsoft Forefront Unified Access Gateway 2010, the W3wp.exe process may randomly stop and cause all sessions to disconnect. When this occurs, you receive the following error message:
A process serving application pool 'DefaultAppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was 'process_id'. The data field contains the error number.
Additionally, an error message is logged in the Application event section of the Windows Logs event log that resembles the following: