Before you fall apart, Po.......it's possible this 'thing' could go away as mysteriously as it arrived. It's not 'skinning ' the square, the monitor is not applying the correct RGB to it. If it's changing color, then there's a good chance it will go away (maybe, even in your lifetime). Look in Display properties/ Settings/ Advanced/ Color Management...make sure it's set to the sRGB color profile. If not, click 'Add' and apply it.