If you hit delete during reboot willit go to bios? If so, the hardware is likely ok. It's possible that there is an interrupt conflict when the operating system loads if this is the case. You might try enabling ECSD reconfigure- or whatever it's called in the bios so that it reassigns the interrupts and see if it cures it for you.
If they don't work in the bios setting mode, it's probably time to RMA the motherboard. Remember- the keyboard plugs into the bottom PS-2 connector, with the mouse plugged in above it- I have seen chassis where the marking was very ambiguous!