.mkv WTF?

sooo.... i cant figure this out.

why (no matter what i try vlc tweaks, MPC, codecs ect) can i get a .mkv file to play cleanly!!!!!

i prefer VLC so if someone has some insight as to what the hell i'm doing wrong please, help me.

(if it helps i'm on my netbook w/ windows 7, other high def video's such as my go pro video's, play fine)