The files probably have ‘header removal compression’ which your player cannot cope with. You need to run them through mkvmerge with the compression turned off. It’s very easy and it does not take long.
http://www.bunkus.org/videotools/mkvtoolnix/faq.html#header_removal_compression
mkvtoolnix
http://www.bunkus.org/videotools/mkvtoolnix/downloads.html
When running mkvmerge, go to file / options and tick box at bottom of list which says Disable header removal compression etc. Add your mkv and then press remux, within seconds or minutes a new file will be made without header removal compression.
