He's talking about changing the CMOS settings or the "boot" menu. More than likely he changed the "enable USB keyboard" setting which can affect the on-board USB controller which then tells "Windows", "Nope, I'm not here".

There is a keypress in the initial start-up sequence which enables a user to change the "start-up" or "Boot" menu. Differs from motherboard manufacturers and also CMOS'es.

Try, "escape", "F1", "F10" or "Insert". Those are the most common. Ya gotta be quick on the newer computers.

p.s., You're too quick for me Danny! I never got my reply posted!