Strange dark areas on screen.
The upper-left corner of my screen has a weird sort of shade over it, making it slightly darker than the rest of my screen. For all intents and purposes it works perfectly fine, it's just driving me nuts. I've unplugged and replugged the cables connecting to my computer, but it still persists. I have no idea what might've caused this. I did drop it off my bed, but that's not that high a fall and was a couple days ago, so I have no clue why it'd start acting wonky now. Any idea why this is happening and how to make it stop?