One last try is making sure the keyboard is plugged into the USB 2.0 port (the black ones) as I've had compatibility issues sometimes with USB 2.0 working properly in USB 3.0 ports until drivers are loaded.
Luck
-=Mark=-
ps, forgot to mention, did you try another keyboard for testing?
psss, I just googled your keyboard and it seems to have this issue quite often. You may want to check there forums for more info or call them direct.
Also, you are using a beta bios, have you tried the most recent stable BIOS (F11)? NM, I see you started having issues with F12e and F11 was fine. Just flash back to F11 and you will be good to go. No need for rma.
Forgot to mention that you should report this keyboard error to gigabyte. I forgot who to send info to, but it should be in the beta bios thread.
http://forum.giga-byte.co.uk/index.php/topic,7410.0.html