This has been ongoing for about six months. Microsoft Support is also clueless.
Periodically (aprox. twice a day [two different users]), Outlook will freeze on a customer's terminal server session, forcing them to force close and start it back up. There is only one symptom that is common between every occurance - CPU usage is stuck at 6%. What's interesting is, the TS had Office 2010 installed, and this happened only to about five users out of the total 45. We tried an upgrade to Office 2013, and now those five users don't experience this problem, but five different users do.
We have about 45 users on a Server 2008 R2 terminal server assigned with 52GB of RAM and 8 CPU cores on a Server 2012 R2 Hyper-V Host (2x Intel Xeon E5-2640).
Outlook is connected to the on-premise Exchange 2013 server - same host, but VM is Server 2012 R2 and has 18GB of RAM assigned with 8 CPU.
This has persisted across two AD domains, three terminal server rebuilds, and two Exchange server installations with new databases per instance. I've rebuilt the Exchange DB, created new DBs, tried to repair mailboxes, etc. Exchange is at the latest CU.
Event logs show nothing in either the Exchange Server or on the Terminal Server in regards to this issue.