[dba-Tech] Bizarre keyboard issue

[Arthur Fuller]

I have a Dell UltraBook. I have never got used to its native keyboard and
built-in mousepad or whatever you call it, and so have a wireless
keyboard/mouse installed on it. When I try to enter my login password,
using the wireless keyboard, I get the message "incorrect password". If I
disable the wireless keyboard, restart, and enter exactly the same password
using the built-in keyboard, it works. WTF?
One more thing. When the wireless keyboard is attached, the built-in
keyboard is disabled. I think there's a setting to change that, but I
forget where it is. (It's Windows 10.) Changing that so I could use either
keyboard would solve the problem, perhaps not ideally, but then at least I
could log on using the built-in and thereafter use the wireless keyboard.
I've never seen anything like this before. All three of my computers have
identical Logitech wireless keyboard/mouse. None of the other two exhibit
this peculiar behaviour.
Any guesses as to why this occurs? Or how to fix it? Or find that setting
that enables both keyboards?
TIA.

-- 
Arthur