Poor MKV Playback on both Sony Bravia TV and Sony BluRay

[JamboUK]

Ever since the Christmas update to Mezzmo I have been having greatly increased problems with transcoded MKV files playing on my Sony Bravia KDL37EX503 TV AND my Sony S370 BluRay player.

The MKV files start to play without problem. But then 9 times out of 10 the sound starts to drop out, go out of sync with the video and the video appears to speed up and slow. Also on occasion just stopping. The CPU usage of the server during transcoding is a perfectly acceptable 50-60% so it isn't a load issue.

I am currently using the Sony BDP (PAL) and Sony Bravia KDL profiles.

Is it an FFMpeg issue?

Your help with this matter would be much appreciated.