Looks like KB2670838 might be a bit of a pain.  It seems to be messing with some systems, including causing a strange colour change in Revit 2012 as per Color Change in Revit 2012 after Updating Windows 7 – The Revit Clinic

The update seems to be related DirectX, including Direct3D.  You can read more about it at:
A platform update is available for Windows 7 SP1 and Windows Server 2008 R2 SP1

Windows Update sometimes becomes quite an annoyance doesn’t it?  I previously posted about problems with WDDM1.1 and Graphics Adapter WDDM1.2.

As you know, support for DirectX is now an intrinsic part of Revit 3D hardware acceleration mode.

If you wish to install updated DirectX runtimes, go to this link (February 2010 version).

This may or may not help you if you are struggling with DirectX (Direct3D) related problems.

These runtimes are periodically updated. The June 2010 version can be found here.