We have an issue in one of our offices, there are 12 users with identical Outlook setups.
5 of these 12 suddenly started having severe problems with Outlook constantly disconnecting and reconnecting, failing to correctly synchronize folders and failing to send messages. The event log on the client PC didn't reflect anything useful and the only thing we could find on the Exchange server was this error in the Security log:
4816: RPC detected an integrity violation while decrypting an incoming message
RPC requirement is set to False on the server (this is a default setting in Exchange SP1). But Outlook by default encrypts messages so it appears that the Exchange is failing to decrypt these messages. The error message goes on to provide a source IP address for the problem and these all match the specific users with the issue.
Unticking encryption in the affected Outlook profiles is a workaround for the issue, but obviously as many other users are set by default to encrypt, we need to fix the root issue of the Exchange failing to decrypt to prevent issues popping up in future.
We have searched high and low on Google with little mention of this issue.
We are running Exchange SP1 on Server 2008 R2. Client PCs are Windows 7 and Outlook 2010.
Any help would be appreciated.