If it comes and goes, I would be led to believe that th monitor is fine. I would think it is more likely a connection problem. Make sure the vga/dvi cable is completely plugged in and not loose. Also, make sure nothing is shorting the connection on the video card itself. The second one is most likely not the proble, I just had that happen to me (but its rare). One my my slot covers fell down and was shorting the connection causing the screen to be different shades.