I installed the character map app which, yes, gives me a clunky solution to the problem.

Finding and installing a BIOS update for my ASUS motherboard has been a nightmare ... with no apparent end...

If there's a problem with the machine's BIOS then wouldn't I have had the same keyboard problem when I had Windows 8 installed? And as for the drivers, it's a fairly old bog standard Dell keyboard...

I have two desktops using a single keyboard, monitor and mouse via a KVM device. One desktop is running Windows 7 but I've just upgraded the other from Windows 8 to Windows 10.

All was 100% well...