I'm not comletely sure of the issue here, but I'll try and describe it as best I can.

The C4HD channel was showing a movie last night in 16:9 letterbox format. When I flick onto the channel it looks fine, but after 30 seconds or so the aspect automatically changes to a "stretch" type of mode - where the image is stretched at the top and bottom to remove the black bars.
This makes everyone look very skinny!

I've tried fiddling with the display modes and formats but it always seems to change by itself after 30 seconds or so.

Can anyone advise on what I'm missing here?

BTW I only installed this box yesterday and I'm very happy with it so far. It has frozen twice though which I'm assuming has to do with the firmware .17 update.

Thanks

Try checking the settings on the TV itself.
I've had simliar probs and it was the TV that was set on auto aspect and it was changing the picture to what it thought was best..

The TV was on "auto" so I've now set it to "16:9", hopefully this will sort it, if not I'll probably be back!

Thanks