I don't know what's the problem. I'm playing a 4gb 720p movie and it stops every few seconds and shows large squares then looks good for another few seconds, etc. It's wierd because i tested the game Stalker at full resolution (1440x900) and it worked perfect. VLC media player, Win XP. Here's my setup:
My CPU is at 44C and my GPU is 52C. Any help is much appreciated!