wireless, yet PS/2
but it's always worked before, it goes "detecting IDE drives" whilst giving me the option to press Del to enter setup.

I don't know why I said it was F2, but either way f2 doesn't work either.
( sandettie light vessel automatic New Twitter - @bollocksreally, Fri 16 Oct 2009, 14:56, 2 replies, latest was 16 years ago)

Try a wired keyboard.
If the OS hasn't successfully loaded and configured yet, it might not like the wireless keyboard. Plug a standard one in until you can make sure it's happy.
(ThomsonsPier consumes, Fri 16 Oct 2009, 14:58, Reply)

Surely
all this happens before the oS is even looked at.
( sandettie light vessel automatic New Twitter - @bollocksreally, Fri 16 Oct 2009, 15:01, Reply)

You'd think so, wouldn't you?
I've had a keyboard not recognised just because I plugged it into a different USB socket. After the OS loaded and I rebooted, it worked fine.
(ThomsonsPier consumes, Fri 16 Oct 2009, 15:06, Reply)

Often a hardware change will force the machine to prompt to enter setup
If you've got enough memory in there pull a stick out temporarily and it should error on bootup and offer to enter setup.
(bill, Fri 16 Oct 2009, 15:35, Reply)