Can anyone shed some light on this little problem?.

I have a HDD HD mediaplayer in my lounge, it accepts avi/divx etc etc files, pretty much supports any files apart from .mkv, which is where my problem begins.

Pretty much all of the HD content available is in .mkv format, I have succesfully converted .mkv files to divx using conversion software, and when you play it on the PC, it's fine, it's in HD, audio is fine and in sync.

When I play it back on the mediaplayer in the lounge, the video is fine, it's in HD, but the audio, although good quality, is well out of sync

Anyone got any ideas?, would trying a different file format help the problem?, and if so, which format (mp4, xvid), could there be a setting in the conversion I could use that would help?, basically I am out of ideas.

Cheers

Try changing frequency, it could be be a simular issue with the .OGG files.

More to the point, if most HD content is in .mkv, why doesn't your player support it?

For first, try encoding audio in AC-3 with some CBR (not ABR or VBR), like 320kbps.
For second, try encoding video in AVC or H264 with some constant bit rate, smth like 8000kbit/s.

If it's a HD mediaplayer, it's quite strange it doesn't support mkv. See if there's a newer firmware for your player. Could be a bug that causes the problem.