HOLY CRAP -- IT WORKED FOR ME TOO!!!
HOLY CRAPSTICK!!! JUST BLOW INTO THE HEADPHONE JACK!!
Denon AVR 1910 - Digital audio processor purchased in July of 2009. I just had the same problem...picture but no sound.
I called Best Buy's "Geek Squad" home theater team (they're the ones who set up my whole system 4 years ago). Their technicians charged $99.95 to come out to my home, check everything under the sun, only to leave and tell us our Denon processor is broken and we need a new one.
ALL I DID WAS BLOW INTO THE HEADPHONE JACK, AND NOW EVERYTHING WORKS GREAT!
Thank you so much to "baileyannesmom" from 7/9/12 for your post. You just saved me several hundred $$ on a new processor, and now I'm calling back Geek Squad to demand a refund on the $99.95 I already paid!