Assume that you perform a search on mailboxes in a Microsoft Exchange Server 2007 environment. In this situation, the Microsoft Exchange Information Store service may stop responding. When this problem occurs, you cannot access the mailboxes on the server, and message delivery is delayed. Note This problem occurs even after you apply Rollup Update 3 for Exchange Server 2007 Service Pack 3 (SP3).
This problem occurs because of a deadlock between a search thread and a delivery thread in the Store.exe process.
To resolve the problem, install the following update rollup:
2734323 Description of Update Rollup 8 for Exchange Server 2007 Service Pack 3
For more information about the hotfix that is included in Exchange 2007 SP3 RU6, go to the following Microsoft website:
914533 The Microsoft Exchange Information Store service may stop responding on an Exchange Server 2007 server
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.