Unity inverting W and Z keyboard

Hello,

since my day-1 in unity, I've always had to invert the keys W and Z on my keyboard.

This happens both in the unity editor and in unity-made games such as slenderman. It is REALLY frustrating.

Sometimes happens, sometimes not. Sometimes WASD works regularly, sometimes it is ZASD and it seems there are NO reasons why this happen.

What can I do? Why is this happening?

Many thanks!