Looks like your horizontal sync and vertical sync values may be incorrectly specified in your XF86Config file. I'm not currently familiar with any graphical utilities, but the way I would fix this is to edit the XF86Config file manually and change these two lines:
Those are my refresh rates, all you'd have to do is change the numbers around. The horizontal and vertical refresh rates should be specified in your monitor's manual.
"Floating in a dream-like state, I am the emporer of a parallel universe." --Arch Enemy
My xorg.conf file