Does it do it through out the video or once or twice? I have gotten that but never thought anything of it as I was just thinking it was a converting issue. I have to take a deeper look at it this weekend and see if it is just a converting issue or just MKV files. Have you placed it on a computer and played it to see if the same thing is happening? At least I know I could rule that out myself as a problem.
It’s throught the hole video. I played the files (problem accours with every mkv file!) on a pc and it runs without problems, so it is not a problem with the file itself, but you can test it another time to be sure