Microsoft is reporting that a recent Windows update is causing serious problems with many computers that have received it as an automatic update. The update, KB 3004394, was released on December 9 and “is causing additional problem[s] on computers that are running Windows 7 Service Pack 1 (SP1) and Windows Server 2008 R2 SP1. This includes the inability to install future updates, ” according to Microsoft’s official page. The problem does not seem to affect computers running other versions of Windows.
The KB 3004394 update is what is known as a patch, meaning it was designed to fix a known bug. It turns out, in this case, that the patch is a bug and the fix is worse than the problem. The update disables portions of User Account Control. Since User Account Control handles critical security features such as allowing or disallowing changes to user accounts and permissions of installed programs and applications, disabling it causes a variety of security risks and can cause programs and applications to fail. The update also disables Windows Defender, the virus protection built into Windows, leaving computers vulnerable to a trove of malware including viruses and spyware.
On the Windows forums, many users complained of a variety of issues:
Windows Authentication failing to recognize that a Windows installation is valid
System Files being corrupted
BSOD (Blue Screen Of Death) caused by complete system failure
Hardware Drivers failing
Random Error Messages related to User Account Control
The list goes on, but these seem to be the most common problems. Not all users are experiencing all of these issues and some are not experiencing any.