It appears that the buggy fix is now affecting videos loaded with WMP too
As I’ve reported to you this week, Microsoft has delivered a buggy fix on Patch Tuesday that broke down video rendering on Windows XP and Windows 7 in specific apps.While Adobe Premiere Pro, Techsmith Camtasia Studio, and Serif MoviePlus X6 are all affected by the issue, it now turns out that the KB2803821 update also turns black half of the video in Windows Media Player.
Microsoft has already acknowledged the bug and is now working on a fix, so your only choice at this point is to completely uninstall the patch from your computer.
“If you use some of the following software, you may experience issues after installing 2803821. In some cases, WMV video files may fail to successfully encode or decode. Upon completion of the investigation, Microsoft will take appropriate action to help protect our customers. This may include providing mitigations and workarounds or re-releasing this security update,” the company explained in an advisory rolled out yesterday.