Troubles with the skate demo...........

I have my ps3 connected to my reciever with an optical cable and when i first start the demo i hear sounds and then a poping noise and then i get no sound and i look at my receiver and it says error. Is anyone having the same propblem? it only does it on this demo, everything else works just fine.

I have no problems with the sound in the Skate demo, but my sound goes through HDMI.

I hope for your sake that it's just a bug in the demo and not the full game.