[mythtv-users] MythTV 0.24-1.80 - No sound on HD TV recording

[PJR]

I recorded 'The Italian Job' from ITV HD the other day and when I play
it there's sound from the TV broadcast prior to the movie but as soon as
it starts there's no sound what so ever. This despite my AV amp
(connected to the mythbox by HDMI) showing it's receiving 5.1 sound but
no sound out of the speakers.  All other HD TV recordings playback sound
in the appropriate number of channels.  Any thoughts as to what's gone
wrong?   Setting or un-setting Dolby, DTS etc in mythfrontend makes no
difference. The TV decoder is a PC nano Stick 290e which has worked
without fault.