It's related to DRM (Digital Rights Management) in Windows Media player. To solve the issue I did the following:
- Removed the Indiv01.key from the following folder and all subfolders:
- Downloaded ResetDRM.exe (link)
- Set the compatible mode on the ResetDRM.exe to Windows XP
- Run ResetDRM.exe as Administrator (right click)
- Started Internet Explorer and went to the following page:
Windows Media Technologies - Security Component upgrade (link)
This routine fixed my problem.
If you remove all DRM you are deleting your possibility to access your *purchased* movies, tv-shows and/or music so contact any sellers if you can re-download your purschased items after repairing the Windows Media Player.