Apparently has something against PowerDVD 8 movies in Matroska containers (mkv - files) on your hard disk, for both drag and drop, and manually adding the playlist to be completely ignored.
Against this "protection" simply helps a simple renaming of the file in eg "Movie.avi" and Power DVD is in the version I used (8.0.2217) no more problems.
Probably be apparent to a legal problem, which forced the developers to incorporate the protection.



