This is caused by the de-interlacing solution inside the SkyHD box. The 576i sd broadcast is de-interlaced to 576P then output as that or scaled to 720/1080i. The tearing in the text or serated edges you may see on lips etc is caused by the broadcom chip inside the Sky box making the wrong determination as to what sort of process to use in de-interlacing. There is nothing you can do about it other than use scart output for SD and then see how good the display is at dealing with it....likley it will be the same if it has film detection capability.