I have the Onkyo 706 receiver and I run my PS3 and XBOX 360 through it using HDMI cables (1.3a). I have recently bought the Samsung 50" Plasma series 6 TOC.
When I play video games on both systems I get blue pixelation in the dark areas. I plugged the HDMI from both systems directly into the TV and the blueness goes away. So it only appears when I have it going through the receiver.
I recently had a Toshiba DLP and I never had this problem.
I am begging for some help here, I just got my system set up using all HDMI's and I really dont want to have to go back and use optical cables to my receiver and plug directly into the TV.
Calibrate your TV then come back if the problem persists. Avia is the best disc to use for calibration. Followed by Digital Video Essentials and the good old cheap-o route of the THX Calibrator you can find on any Star Wars movie as well as many others.
Always remember: The pessimist is never disappointed.