I would recommend using the component cables to change the output to HDMI and then making sure you have a supported resolution (720, 1080i, 1080p) selected. You might want to check that the boxes are also programmed to output in HDMI, as it may be a setting in each box. If you've always used component, you often have to tell the box, blu-ray player, etc to use the HDMI to send the signal.
Keep me posted.
I am trying to get my Pioneer Elite SC-05 Receiver, Pioneer Elite BD-05FD Blu-Ray Player, and Time Warner HD Cable Box to work with the Samsung LN52A650. I have tried HDMI 1, 2, and 3. With the bluray player and cable box it says mode not supported - with the receiver I don't get that message, but the screen shows static, then goes black, then static again over and over again. All 3 work fine with component and composite connections. Samsung said to try a different HDMI cable, which I only had one at the time - but I am not confident that is the problem. Any suggestions? Thanks!!!!!!!!!!!!!