Some mkvs play some dont

[TheApocalyptican]

I am trying to play mkvs over my network. They are all generally the same size. All are 720p, all are 5.1 dts. Some play just fine, the others jump to the end of the seek bar, and to 536:Xx:Xx of the video. Obviously the videos aren't this long, and the time that shows up like that is the same number every time, despite the videos themselves being different length. Anyone had this problem? Or have any ideas on fixing the problem?