OK, 1st, I think you meant mkv, not mvk. Second I have tried 24hz and 60hz, and both work, but I am currently set at 60hz. Why, is easy. PowerDVD 12 Ultra (my BD player) switches Aero off in 24hz, and not at 60hz. I use the currently at half price Splash Pro EX ($29.95) for .mkv because with no codecs, it plays Master and TrueHD .mkv files as Master or TrueHD audio. VLC will not, you only get DD or DTS with it.
So, do you have any Master or TrueHD .mkv files? I have many now (my disks are all stored), so Splash Pro EX was a great buy! It will play mts as well, but I am unsure about iso. I know PowerDVD will if I use a disk mounting software and mount the iso file.
Of course, XBMC may do it all for you as well. Someone else may know if can play iso files.