The Microsoft Exchange Information Store service (Store.exe) crashes. Then, a failover between database availability group (DAG) members occurs. When this issue occurs, you cannot connect to your mailbox.
To resolve this issue, install the following update rollup:
2936871 Update Rollup 6 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.