KB Article: http://support.microsoft.com/kb/2575360
This article introduces a new feature to automatically stop the Microsoft Exchange Information Store service when a time-out is detected.
Currently, when a transaction lasts longer than 60 seconds on a Microsoft Exchange Server 2007 Service Pack 3 (SP3) server, a time-out detection event is logged in the Application log. This may indicate a deadlock when the transaction happens. When the deadlock occurs, the Microsoft Exchange Information Store service stops responding.