My dad's ThinkPad L412 has got a small dark spot on its screen. It's not completely black, it's a grey irregular shaped (almost circular) spot. I thought it was a dirt particle so I tried cleaning but that didn't help. The spot's diameter is hardly half millimeter and is hardly noticeable except if there is a solid color displayed in that area. I have confirmed it is NOT a stuck pixel because a stuck pixel shows varying colors depending upon the color displayed. If it is a dead pixel, it must be black. But it is not. It is very very light grey in color and appears the same no matter whatever is displayed. I tried many dead pixel apps but none helped. Can you help me sorting out what exactly that spot is?