I recently bought a Sharp XV-Z91E Projector and I am generally very impressed with the picture quality. However occasionally I have noticed the presence of an odd appearance where there is some greenish speckling over dark areas. I noticed it particularly on the underwater submarine sequence in The Phantom Menace. According to the projector magazines this is a problem that is common to DLP machines. I find this more of an irritation than the oft mentioned rainbow effect which to me is hardly noticeable. I am currently projecting onto a magnolia wall and I wonder if this is adding to the effect. I am considering buying a screen but I am unsure as to whether it will make any difference. Any thoughts?