When the Microsoft Exchange RPC Client Access service (Microsoft.Exchange.RpcClientAccess.Service.exe) freezes in a Microsoft Exchange Server 2010 environment, users cannot connect to the Client Access server until the RPC Client Access service is restarted.
This issue occurs because of a deadlock in the RPC Client Access service.
To resolve this issue, install the following update rollup:
2891587 Description of Update Rollup 3 for Exchange Server 2010 Service Pack 3
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the RPC Client Access service, go to the following Microsoft website: