Go to your card settings and find some settings who is for tv or hd quality, change settings and try each time what is hapening with hd movie. Please start each time movie (player) again. Do not use play pause. Every time close and start player again.
There must be settings issue in your graphic card
I've upgraded to a sapphire hd 4650 video card. it's done wonders for the aero and game graphics rating on windows 7, but now when I run HD movies it doesn't look as good as when I ran them on the integrated graphics card. I've done driver update after driver update, again and again, and I've seen no difference. This is a pain because I bought the card particularly for it's HD capabilities. Could someone help me with this?