Thanks for this. I've given this a shot but the couple of alternatives have not semed to work (but in saying that the apple logo and a green screen flash up on hte TV for a seond or so before returning to the 'no signal' screen). The previous sertting was 'detect automatically' so I changed it to 780 then 480. Is there a resolution you would suggest? The TV I am trying to use it on says it is 1080 (and it has owrked fine on it in the past with the same cable).