Im using a an Acer Aspire Revo R1600 and for some odd reason with this new version of Ubuntu i can't play .MKV files anywhere. I have always had flawless playback but now im getting a weird message from the video player.

"Could not find GStreamer caps mapping for FFmpeg codec 'h264', and you are using an external libavcodec. This is most likely due to a packaging problem and/or libavcodec having been upgraded to a version that is not compatible with this version of gstreamer-ffmpeg. Make sure your gstreamer-ffmpeg and libavcodec packages come from the same source/repository."

I tried installing the restricted extras and playing it back in VLC but in VLC i just get a green picture and thats all.