I have the same problem.

I plugged my monitor on a PC without this problem and the bug appears

Turns out to be an hardware issue. Try the several colours preset of your monitor or adjust your constrast / brightness by yourself.

I don't know why but, it looks like it's something about how our monitor renders the colours.

PS : I have two BenQ GL2460

EDIT :

The bug disappears when :

1. I am in the graphical settings (when I play)
2. Reduced when using SweetFX
3. Changing my colours settings on the monitor

And If I recall correctly, that was not from the beginning, this bug appears after a patch (I don't know which one)