This started to appear in my Vista x64 event log after changing the CPU. Side effects visible elsewhere included inability of Windows Movie Maker to split Media Center recordings and crash of Windows Media Player 11 when playing Media Center recordings.
Error 0xC00D278F refers to NS_E_DRM_HARDWAREID_MISMATCH, which is described at “Windows Media Format 11 SDK Error Codes”. Judging from the description, this error would mean that any hardware change could provoke it. Even as innocent as CPU change or upgrade of graphics card (Google found at least one report of upgrade from NVIDIA 6800 to 8600 causing exactly the same symptoms). The solution is available in ME891664
. In short, all files have to be removed from the folder "%SYSTEMDRIVE%\ProgramData\Microsoft\Windows\DRM". After that, you can re-individualize DRM system by going to “Security component upgrade“, and clicking on upgrade button.
Unfortunately, there is no simple and visible warning for less experienced users that their DRM files became unsynchronized with their hardware.