Symptoms
When this issue occurs, you receive a warning message that states that the sharing session has stopped because of a monitor resolution change. This issue occurs when you have multiple monitors. This issue also occurs when you share a monitor, and then you plug in another monitor, such as a projector.
Resolution
To resolve this issue, install the December 9, 2014 update for Lync 2013.
Note After you install the update, when this issue occurs, the sharing session will pause briefly, and then it resumes.
More Information
This issue occurs because the underlying RDP stack automatically pauses the sharing session.