Boot by spacebar stopped working

Here's a puzzler for you. I have an Asus P9X79 system which I've been
using happily for almost five years now. The other day I pressed the
spacebar to start the system, and nothing happened. That's weird -- I
always boot by pressing the spacebar, but pressing the button on the
case started the system, and I went merrily on my way not giving the
problem much thought.

But the next time I tried to boot, the same thing happened, so I checked
BIOS and found the boot by spacebar option was disabled. Well that was
weird, as I hadn't been into BIOS in months. So I enabled the option
and shut down and then pressed the spacebar -- and nothing happened.

Now I did recall that a day earlier my (USB) keyboard wasn't working and
when I checked I found I'd dislodged the USB to PS/2 adapter plugged
into the MBO. So I pushed the adapter back into place and the keyboard
started working again (after a reboot) and I was in business. But now
I'm thinking maybe this was the start of my spacebar boot problem?
Could this be what disabled the option in BIOS? I dunno.

All I know is that now for some reason I can't boot from the keyboard.
Even changing from the spacebar option in BIOS to the Ctrl/Esc option
makes no difference. Suddenly after all these years, how is is it that
I can't boot from the keyboard? I know the keyboard is getting power
from the MBO even in the shut-down state, as I can unplug the keyboard
while shut down, and when I plug it back in the lights on it flash. But
it won't boot the computer.

Maybe I need a new MBO battery? The clock is giving me no problems.
Other ideas anyone? Help?

--
Bill Anderson

I am the Mighty Favog