Stuttering video on VOB and MKV mpeg2 files

Hi I just Updated the Media player and also updated to Lion and now I have problems with stuttering video mainly vob and mkv(created with makemvk no recompression) It used to play fine fine but now it stutters and it is unwatchable!! I use a Wireless N connection and a Gigabit router and both the video files stutter!!! But the HD 720 H264 mvk files play just fine!!! even a 1080 h264 plays fine via wireless!!! Then I converted one vob file that was stuttering to an h264 mkv with handbrake and it Played just fine!!  Does the new media player have something wrong with vob or mkv mpeg2 files? Before the new update the files played fine!! I am using the latest media player and Lion!! Anyone with the same problem?