I've had a problem with MKV files stopping after a few minutes when using Mezzmo or any other media streaming software on my MediaSmart WHS. Twonkey, MediaConnect, etc. all have the same problem. I stream to an ethernet-connected WDTV-Live for display on a Samsung UN55 tv. The interesting thing is that the same MKV files play fine if I use "network shares" instead of streaming software to play them (this would be fine, but the interface is a bit more confusing for the rest of the family).

I knew this wasn't entirely a Mezzmo issue because the behavior was the same no matter which streaming software I was using. But because its a common issue on the WDTV-Live forums, I thought I would post the solution here as well.

I downloaded MKVToolNix from http://www.bunkus.org/videotools/mkvtoolnix/index.html and installed it. I used MKVMerge (the program in MKVToolNix) and put the problematic MKV file as the source. It appended a "(1)" to the file name for the output file, and I let it remux the file. I renamed the original file and then renamed the new file to the movie's proper name. It now plays fine when streamed by Mezzmo.

I don't know why the original file would be fine when streaming from a share, but choke when streaming through streaming software like Twonkey, MediaConnect or Mezzmo. I suspect my original ripper (MakeMKV) had some kind of error in the output file that chokes DLNA-compliant software. In any case, this fix seems to have done the trick (fingers crossed - I'll update this if the fix doesn't work with the rest of the problematic files).