Loss of HDMI on Denon 2910

Hi Guys

I have a puzzling problem with my Denon 2910. The denon has been connected via HDMI to a Denon AV amp then onto my Panny screen and working successfully for the past 10 months until last night when it refused to output picture and sound via HDMI.
I have plugged the Denon directly into the Screen and still it refuses to work. I then replaced the HDMI cable agin directly into the screen and still no joy. I have tested other HDMI sources into the amp and screen and have no problems everything else works as it should so I'm convinced it's the Denon 2910.
I have checked the DVD setup and HDMI is enabled. When I connect using component I have no trouble. The trouble is with the HDMI connection of the 2910.

Has anybody else experienced this?

It's not a major problem as I prefer the component output to the HDMI as it seems to introduce less artifacts. I'm just curious to know why the HDMI has stopped working.