"Get into CMOS Setting"? What are you talking about? CMOS is not used in modern PCs (well, other than to store the date and time); firmware (BIOS) configurations are stored in flash.
Do you mean enter BIOS Setup (Visual BIOS)? If you press F2, does this result in Visual BIOS being displayed? Always? If you do get into the Visual BIOS display, are you saying that it subsequently hangs? If so, what were you doing when this hang actually occurred?