UPDATE: Microsoft just announced that they have temporarily removed the update. For more details see: KB2830477 KB2830477 was released Tuesday November 12 2013 and updates the RDP Client on Windows 7 to RDP 8.1. After installing it we have experienced issues with Smard Cards no longer being available in the remote session. Uninstalling KB2830477 solves the problem. So if smart card authentication suddenly stopped working on your windows 7 clients, check if you got KB2830477 installed.