Need advice about Samsung LCD tv problem
 

I have a friend who bought a Samsung LCD 120 hz tv, 40-42 inch I believe. Don't know model number. Anyway, he sees a brownish blotch in the upper left hand corner of the screen when he watches mostly black and white shows. It just swhowed up a couple of weeks ago. Is there a refresh button or something that will clear that away? I have a Pioneer plasma and there is something like that for burn in, so does anyone know if LCDs have something similar? He doesn't know where his manual is.