Let’s ask the source of all earthly wisdom:

Legends tell of three major types of kobolds. Most commonly, the creatures are household spirits of ambivalent nature; while they sometimes perform domestic chores, they play malicious tricks if insulted or neglected. Famous kobolds of this type include King Goldemar, Heinzelmann, and Hödekin. In some regions, kobolds are known by local names, such as the Galgenmännlein of southern Germany and the Heinzelmännchen of Cologne. Another type of kobold haunts underground places, such as mines. A third kind of kobold, the Klabautermann, lives aboard ships and helps sailors.

https://en.wikipedia.org/wiki/Kobold

To be fair – the error message right after the POST which was produced by switching PS-2 mouse and keyboard was more than cryptic and gave no indication what so ever on the real reason.

Back in the day keyboard and mouse were connected to the back of the computer with identical (but color coded) PS-2 plugs.

Today one would expect that swapping two mechanically identical plugs would result in no major trouble - think USB - but back then COLOR CODES HAD TO BE OBEYED!

Or computer science teacher came to help when our PC won’t boot up, tried reset, tried reset again, fiddled with the BIOS, gave up.

That wasted more than halve the lesson’s time just for us to swap plugs back to working while he wasn’t watching.

Sometimes things simply don’t work when the teacher is around…

Xubuntu - back from the days with a slightly slower laptop.

Same over here in Germany. The safety regulations for tap water are even stricter than for bottled water