I occasionally have a problem with some recordings made from HD channels in that, when I start to play the recording, there is no sound.

Stopping the playback, going to another recording, starting to play it, then going back to the original recording and possibly repeating the process more than once seems to put the problem right but I have been unable to determinine what causes the problem nor what precise series of manipulations I need to do.

Any ideas as to what might be causing this or what I need to do in order to prevent it from happening?

Asuming you use a TV for sound it's probably the TV having a problem with the dolby digital audio used on HD channels.

Try forcing the box to output lpcm stereo.

Menu/Settings/TV Setup Dolby Digital - off.

Thank you. I will try this.