I've had my InFocus Screenplay 4805 for just over a year now (my first projector -- love it). Recently, I've noticed what appears to be dust inside the lens(es). It's most obvious when the projector first switches to the source and the screen is black. I can see white "blobs" in several areas that are consistent day to day. When I look into the lens (from an angle), I can see what looks like dust accumulated on an interior lens. I've cleaned the exterior lens and that did not fix anything. How can I clean this? How can I prevent it from happening in the future? Thanks!