I have two PCs running Windows 7 pro on a Windows 2008 R2 Server domain that are experiencing the same issue. The common factors seem to be both use GoToMyPC for remote access, both use SonicWALL/McAfee enforced antivirus and both problems seem to be related to a Windows update. The problem is that when the domain user tries to log in at Ctr-Alt-Del they receive an atbroker.exe error and the screen goes black with just the mouse cursor and stops. The system will boot into safe mode and can log on as administrator. I have tried the suggested Ctr-Alt-End but this does nothing. It also seems there may be a timing issue of something starting up involved because if the system is rebooted numerous times it will occasionally log in correctly.
I was only able to resolve the first PC by a reload and am trying to find what the problem really is. Going back to a earlier restore point did not resolve the issue. Thanks