How-to-solve : C00D11B1 error when trying to play files in Windows Media Player 11 or MuvAudio
A soundcard driver that you have installed on your system has an unsigned sAPO which, to work, creates a registry key. The key is then causing the C00D11B1 error when trying to play files in Windows Media Player 11 or MuvAudio. To fix the problem, please do the following (WARNING: at your own risk, as modifying the registry incorrectly can cause issues):
1. Click on the Start Menu.
2. Type regedit into the Start Search box and hit enter.
3. If asked for permission, click on Continue to open the Registry Editor
4. On the left-pane, navigate to the following: HKEY_LOCAL_MACHINE, then SOFTWARE, then Microsoft, then Windows, then CurrentVersion, and finally, Audio.
5. In the right-pane, double click on the text, DisableProtectedAudioDG, and change the value from 1 to 0.
6. Close the Registry Editor.
7. Restart your computer.