|Do NOT use a wireless keyboard.|
Do NOT use a front USB port or one that runs through a USB hub, including internal hubs and 3rd party USB motherboard ports (only USB ports directly on the chipset will be active at that boot stage).
PS2 keyboards are good if you have one and there is a port for it. Otherwise follow above and try the USB wired keyboard on more than one USB port. On many early motherboards that included USB3 ports, some and sometimes all USB3 ports ran through 3rd party USB controllers. Drivers for these are not fully functional until after Windows drivers are loaded. Because of this, if you have USB2 and USB3 ports, use one of the rear USB2 ports.
You have to be a little bit crazy to keep you from going insane.