something odd with htpc signal to receiver

My living room HTPC died a week back so I decided to move the bedroom htpc up to the living room until I get the other one fixed. The bedroo htpc is a Zotac 8200 mini-itx system outputting via HDMI to onkyo 6100 receiver outputting via hdmi to 50" plasma. First time trying to hook it up last night was somewhat of a failure.


First off, I could not find an overscan option in the nvidia control panel so the desktop was strectched in all directions too far. The only thing I could do is set it to a lower resolution(720p) and then "resize" the desktop so it fit the screen. I could not do this when it was 1080p. It was shown being stretch to fullest extent.


Secondly, tried to watch a bluray on it using powerdvd8 (resolution set back to 1080). If I tried to watch it in fullscreen mode, the receiver would constantly switching back and forth between something and multichannel pcm basically giving me no sound. BUT when watching it in a windowed mode, there was no problems. It played the whole movie without trying to switch decodes.


So that left me to think that it for some reason was recognizing that the fullscreen was taking up more than 1080p and was thoroughly confused on what to decode.


Anybody have any thoughts?