> > >Is there anything in the area that bears this pattern?
> > >
> > > Its sudden disappearance would probably be due to either the casting object, or the light source that's reflecting off it (the sun?) moving out of alignment.
> >
> > It's in the second picture...the wire thing on the right.
>
> That wire thing is the cord on the blind.
> Howard

Well..it was hard to tell what it was in the picture, but it does have the same tic-tac-toe pattern at the top.