Unplugged TV plus rolled back drivers on media center pc OK!
I fixed the problem for now by unplugging my tv and then plugged it back in and adding the HDMI source components one by one. Now the TV shows both on the proper source ports and does not appear to be confused. To get the sound to work for my media center PC over the HDMI link I had to install the latest realtek and nvidia drivers for my media center pc from the HP website. I had newer drivers for both installed, but apparently they conflicted or did not play nice with my media center pc. I'm running an HP Pavilion Elite m9040n, a Samsung pn50b650 HDTV and a Samsung bd-p1590 blu-ray player. I'm not happy that the TV's HDMI processor is so finicky.