1) Unplug the computer; hold power button for two seconds to discharge remaining energy in board/PSU capacitors
2) Clear the CMOS
3) Boot the computer and check again
I know it sounds like a simplistic procedure, but it's solved weirder behavior than the mouse thing you've mentioned.
I would also recommend trying another mouse -- no way ASRock lets this kind of bug get past. I'm sure they test this with standard mouses -- it's possible you have an unusual mouse that the BIOS is having trouble with.