PSP LCD Black Corners

My PSP's screen has a black corner, and I don't know if it's a burned out crystals, or just random. I think it's because I always leave my PSP on when I go do something, most of the time forgetting that it was on, which means I always leave it on for hours.

is it always there?
if so you should change the screen.

Proabably the pixels asre dead, many things can happen to the screens but none display those symptoms other than pixels dead or on way out.