Can you try the following:
Let it reboot at default values and than shutdown normally. Wait and
startup again than enter the BIOS and than do your settings BUT do NOT set CPU FSB yet (let it on auto) and reboot again, let it startup windows. Than shutdown the last time and reboot and enter the BIOS once again and set the FSB to whatever OC you used.
This works for me! I can shutdown/reboot without having to set the BIOS again.