I've noticed this problem with a TV (I'm using SCART and non-interlaced with ArcadeVGA) when the brightness and contrast are set to normal-high level. It seems that there's some distortion caused by white colours, or light areas affecting other areas... but I don't know really what's the origin or the reason. Does this happen also with Arcade monitors? When I reduce brightness and contrast this problem fades away. Can anyone explain why this happens?