You disconnect and then reconnect a remote session to a Remote Desktop Server computer that's hosted in Citrix XenDesktop 7.6 (for example, by locking and unlocking your computer screen). In this situation, Microsoft Lync 2013 (Microsoft Skype for Business) may crash. Additionally, the following event is logged in the Application log:
This issue occurs because some code elements that used to check NULL device pointers are missing from the current file.
To fix this issue, install the January 12, 2016 update (KB3114502) for Lync 2013 (Skype for Business).
Note Lync 2013 was upgraded to Skype for Business in April 2015.