try resetting the CMOS which will reset your bios to default
but if you dont know how to reset the CMOS the normal way then... look for the circle battery on your motherboard and remove it for 5 secs, put it back in and it will reset your bios.
P.S it will also reset the date and time on your computer.
I've just tried that and it's the same.
I'm hoping it's a specific BIOS setting or a hardware fault. I sure hope it's the former.