For the last several days, when watching an hour-long show, WMC crashed 2-3 times for me while using RTVHD. I reviewed what had changed on the DVR, and the only change was installing Microsoft security update KB2993651 on my Win7x64 PC. I rolled it back, rebooted, and haven't had any further issues.
KB2993651 was a replacement update for KB2982791. In the corresponding security bulletin, Microsoft strongly recommends manually uninstalling the old update before installing the new one.
It should be noted that KB2993651 was released with two issues (below). If anyone else experiences my issue, try rolling back KB2993651 and rebooting and see if that resolves the issue. Hopefully, a replacement-replacement update is on its way.
Do you know if either of the below Known Issues would affect WMC and/or RTVHD?
Known Issue #1:
After you install this security update, fonts that are installed in a location other than the default fonts directory ( percentwindir percent\fonts\) cannot be changed when they are loaded into any active session. Attempts to change, replace, or delete these fonts are blocked, and a "File in use" message is displayed.
Known Issue #2:
After you install this update, the z-order of the windows is changed. (The z-order calls the SetWindowPos function together with the HWND_TOP parameter.) Therefore, the windows of certain applications may become invisible or may be incorrectly displayed behind other windows.
We are currently working on a resolution for this issue.
This issue also occurs after you install the following updates:
2965768 Stop error 0x3B when an application changes the z-order of a window in Windows 7 SP1 and Windows Server 2008 R2 SP1
2970228 Update to support the new currency symbol for the Russian ruble in Windows
2973201 MS14-039: Description of the security update for Windows on-screen keyboard: July 8, 2014
2975719 August 2014 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2
Todd Cassell at the Bentley Technical Support Group has more details on this newly announced z-order bug:
The issue was first introduced in KB2965768 on 5 Feb 2014. In that version win32k.sys makes changes to the z-order of the windows. That z-order calls the SetWindowPos function) . KB2973201 (8 Jul 2014) and KB2982791 (12 Aug 2014) also contained these changes to win32k.sys. Updates that affect the behavior of the toolboxes as well are: KB2970228 and KB2975719. The issue may also be in other security or service updates released since 5 Feb 2014. The last well working version of win32k.sys (Windows\system32) is: 6.1.7601.22665 from 23 Apr 2014.
Due to dependencies with .dll and other files, just replacing win32k.sys is NOT possible and will result in system crashes. Currently the only solution is to uninstall KB2965768, KB2970228, KB2973201, KB2975719, KB2982791 and KB2993651.as that will bring win32k.sys back as the working version.