Windows 7 - xbox 360 media center extender and mkvs

so i want to playback mkvs on my 360 down in the basement and i know it can play mkv files... about a hand full of the mkv 720p files i have will steam fine were as others say missing file is needed to playback... im guessing its due to the encoded of the video file so my question is what is the best encoding program for me to reencode my mkv files that arnt currently compatiable with playback on the 360 also i dont want any quality loss

It's probably more the video itself that is causing problems versus the container itself but regardless. Handbrake 0.9.5 will do a full re-encode for you. The biggest thing is to make sure you have a whole-hearted H.264 video "core" (so to speak), MPEG4, or MPEG2. Anything like MPEG2-TS or XVID may cause issues inside an MKV container (from my experience).

Personally, I make sure ALL of my videos are H.264 (RF 20) inside an MPEG4 container, but that's just me. It plays on everything.

i will try handbrake i dont believe its the video itself altho who knows really but they all work perfectly fine in vlc media player i have the same problem with my wd media players

Sometimes there can be just the slightest tweak to the container. I know that QuickTime doesn't like any more than 1 B-Frame (unless they've fixed it) in H.264 videos. MKVs can be tricky for media extenders like that. I know my PS3 won't play them at all. Switch to MPEG4, or hell, even XviD inside an AVI file and it's fine.

VLC (and even MPC) are like cockroaches of the media player world. They take a hell of a lot.

i used handbrake and converted them to mpeg4 and they work fantastic thanks for your help

Great to hear! Containers make all the difference.