Well, the screen I ordered has Tunnel Vision.

One thing I noticed on this screen, in the corners where the screen was turning "black", it wasn't losing the ability to display an image, but the polarity of the liquid crystals had inverted. When I moved my pointer into that area of the screen where it had darkened the color of the pointer inverted, but other than that it looked perfectly normal. When I moved the pointer into an area where that was unaffected by the darkening it went back to its typical color.

Does anyone know what could make the liquid crystals in the corners of the monitor invert their polarity like that?