Sugar Outlook plug-in disconnects Outlook when sending and receiving

We are experiencing issues with the Sugar Outlook plug-in on three CRM instances (two on 10.0.4 and one on 12.0.3) while using Outlook 2302 and CRM Plug-in for Outlook 2.7.7. 
When attempting to send and receive, Outlook disconnects, but we can still manually archive records to CRM. Disabling the plug-in COM and restarting Outlook resolves the issue until we enable the plug-in again.
We received a Sugar Log error message  [VSTA_Main] WARN Sugar.Outlook.Outlook - Network problems are preventing connection to Microsoft Exchange. 
So far, we have been unable to replicate the issue using either an admin or test regular user account. 
Can anyone offer suggestions?
Regards
Christopher