Graphics overlay feature GeForce cards - help me

Does anyone know how to disable the graphics overlay feature on GeForce cards? When I watch AVI's or DVD's the screen is zoomed in slightly and a bit pixelated (blocky) and the WMP10 and Power DVD controlls are off the edge of the screen. I've set the zoom option to "fully out" and can remember ages ago an option somewhere to turn off video overlay completely which sorts out the zoom and the images are crystal clear again and I can also see the controls. Any ideas please :)

In the settings of the media player are where you can turn off video overlays.

Thanks - didn't think to check WMP as I don't use it anymore.