@Seminole
Not 100% sure on this shipmate but I think its because your not at native res (I'm guessing you are flat panel?) Same happens here when I'm not running native. I got my ears open if I'm wrong tho. One question mate do you by any chance use driver version 257.xxx, if so do you use Nhancer? If so it might be worth you reading this:
http://forum.nhancer.com/showthread.php?t=1768
Best regards.
Fubar2Niner