Two different players will not play mkvs properly (black screen and player locks up)

I will paste the details of one of the files when I’m back home but so far the only player that gives me any issues with mkv files is the wdtv player.  I have tested different tvs and dvd players that all support playback from a harddrive.  The same movie plays perfectly.  In all honestly, if I knew tvs / dvd players were able to play mkvs as well as they do, I would have never purchased these players.

I have the wd tv players using the latest firmwares + hard drive directly connected to the players.   The black screens happens randomly.  it is not in the same spot always