I think I have one avenue for you to check:http://www.tech-faq.com/mkv-file.html
Troubleshooting MKV File Problems
If you happen to download a file that has an .mkv extension and you just can't play it, this advice should help you out:
Make sure you have the latest codec pack downloaded. A codec pack is a collection of the most common and latest decoding drivers that will enable you to play a variety of multimedia extensions including .mkv files. Also, a VLC Player, which do not need additional codecs, could be the easiest and reliable player to play .mkv files.
The link recommends VLC if you have problems playing .mkv files.
Here’s the link for more info/download:http://www.videolan.org/vlc/
I have VLC and use it extensively. I have yet to find anything it won’t play… and it’s free!
Also, I found this codec guide if the above doesn’t work and if someone else wants to take a stab at this:http://www.codecguide.com/faq_dxva.htm