The information store is dismounted, and an event ID 1159 message is logged in Exchange Server 2003 or in Exchange 2000 Server

SYMPTOMS
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In Microsoft Exchange Server 2003 or in Microsoft Exchange 2000 Server, the information store is dismounted. Additionally, an event that is similar to the following event is logged in the Application log on a server that is running Exchange Server 2003 or Exchange 2000 Server:
Event Type: Error Event Source: MSExchangeIS Event Category: General Event ID: 1159 Description: Database error 0xfffffd9a occurred in function JTAB_BASE::EcUpdate while accessing the database "". Note The error code 0xfffffd9a translates to JET_errCheckpointDepthTooDeep.

http://support.microsoft.com/kb/905801/en-us

Keyword: event ID 1159