Lately I’ve been having issues after applying updates to Windows Server 2008 R2 machines where after they are applied I am no longer able to access them via Remote Desktop. 

Issue/Error

Unable to connect via Remote Desktop to server after applying SP1, receive error below:

“The remote computer returned an RDP protocol error (Return code: 50331670)….”

Resolution

The issue is related to SP1, and the link to the hotfix below resolves this issue.  Hopefully you are either local or have another solution such as RealVNC installed so you can still access the machine and apply this update AFTER SP1.

KB2667402:

A security issue has been identified that could allow an unauthenticated remote attacker to cause the affected system to stop responding. You can help protect your system by installing this update from Microsoft. After you install this update, you may have to restart your system.

http://www.microsoft.com/downloads/details.aspx?FamilyID=3A6C7FDF-105A-4886-AD52-C892F37E32D1&displaylang=sl&displaylang=en