I have been managing a large Remote Desktop Services (RDS) environment running Windows Server 2012 R2.  On occasion, we have noticed the session hosts theme randomly go black.  It looks similar to a photo negative or the High Contrast theme setting in Windows.

Here is the fix for this issue:

  1. Navigate to C:\Windows\Resources\Themes\<yourtheme>\VSCache
  2. Show Hidden Files
  3. Take ownership of the VSCache folder.
  4. Delete everything in the VSCache folder.
  5. Reboot the server.  Windows will recreate the corrupted files and the issue should be resolved.