When Microsoft Outlook is used in online mode in a Microsoft Exchange Server 2010 environment, the Microsoft Exchange RPC Client Access service (Microsoft.Exchange.RpcClientAccess.Service.exe) stops unexpectedly on the Client Access server. When this issue occurs, users cannot access their mailboxes until the RPC Client Access service is restarted. Additionally, you see the following event in the Application log on the Client Access server:
This issue occurs because an incorrect argument is passed to the Microsoft.Exchange.RpcClientAccess.PropertyValue.CheckValueTypeOnConstruction function. Therefore, a System.ArgumentException exception is thrown.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.