The store.exe process on a Microsoft Exchange Server 2007 server may hang. As a result, the mailflow to the Exchange Server 2007 server is blocked. Eventually, clients cannot access the mailboxes that are located on the Exchange Server 2007 server. Additionally, if you monitor the RPC Averaged Latency of MSExchangeIS in Performance Monitor, you find that the value of the RPC Averaged Latency of MSExchangeIS is very high.
This problem is caused by a deadlock in the store.exe process.
To resolve this problem, install the following update rollup:
979784 Description of Update Rollup 3 for Exchange Server 2007 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.