I have a Samsung 40" LCD 4065 with a shuttle Windows XP pc attached over HDMI->DVI. When I run games using DirectX or video in Windows Media Player full screen I get "snow" on the screen. This is in the form of white pixels randomly interspersed through the display very lightly (although frequency sometimes depends on the game and resolution). It's noticeable on dark/black backgrounds and a little annoying.
It only happens in games/video (including the entire display if there is video or a game running windowed) and not normally on the desktop or other applications. It also only happens when there is motion on screen, if the game/image is paused it stops.
The PC is running 1920x1080 desktop resolution at 60Hz refresh rate, and the refresh rate for Team Fortress 2 is the exact same as when I run the Xbox 360 version over VGA. Any ideas what else this could be?