Similar problem with me.
I've been trying to fix my home PC for days now. Has a "keyboard error" at startup and it keeps on re-booting. I suspect the "pc booster" program OR the Windows update itself messed my system..
If you have a usb keyboard, it usually comes with a USB-PS/2 adapter. If you want to eliminate the keyboard as a factor, you need to boot up with the keyboard hooked up to a PS/2 port.
Once the pc boots into Windows, the keyboard can go back to the usb connection.