Odd Keyboard Problem

[RVB]

I have several old computers.

During lockdowns a few of them were found to be able to play old PC games while also running Windows 10, which helped the kids with boredom.

An odd thing that I haven't yet resolved involves a couple of Dell Optiplex 780 models.
With one of the computers, for some games, the left arrow key will perform both its own assigned function and simultaneously perform whatever is assigned to the numberpad 4 key.
Similarly, the down arrow key will perform its own function and the numberpad 2 key function.

Even if I go into the game settings and don't assign anything to the left arrow or down arrow, they still activate what's bound to the numberpad 2 or 4 keys.
I've tried more than one keyboard/mouse on the oddly behaving computer but it makes no difference. I've tried uninstalling and reinstalling certain games but that hasn't helped either.

Any ideas what's going on?

Thanks,
R

[Bacon Is Proof]

Does NumLock make any difference?

[RVB]

Thanks for the suggestion but this morning I seem to have resolved the problem so I am reporting back to complete the story.

I had a close look at every setting, update, driver etc on the two computers and found one difference; the BIOS.
On the computer which worked normally it was 1.10 A15 and on the one with the misbehaving keyboard it was 1.10 A03
.
I went to Dell's website and downloaded/installed the 1.10.A15 BIOS and it now seems to have cured the misbehaving keyboard issue.