Advice please from anyone that has purchased this set. I took delivery of the set on Wednesday and have been blown away by the quality of the picture. However when changing channels or going to an untuned channel you have a black screen and I can see a faint light in bottom left hand corner of the screen and the top right and a little in the top middle. You don't notice this much when there is a picture but in really dark scenes in a film you can notice it slightly. Is this normal with LCD's as I'm not sure whether to ask for another set?