Well if error is occurring due to DRM protection then you can remove the protection from your music and video files and then you will be able to easily play your media files (music and videos). In order to remove DRM protection you will need DRM Media Converter.
Key features of DRM Media Converter
-Support a large number of DRM audio and video files
-Output DRM-free audio and video files for different devices and players
-Also can handle common audio and video files
To my opinion, DRM Media Converter is better than other similar product. It works faster, and can remove DRM from iTunes purchased and rental movies/TVshows. The most valuable for this app is that it can easily remove the DRM protection from Video and audio files as well as Ebooks purchased or downloaded from iTunes. There is no quality loss at all in the output videos, audio or ebook.