Just for the record: what "relatively calm antivirus" software did you install?
I would not consider Windows Defender as being a culprit. There have been past flaws but I have not seen or heard of such problems for quite awhile.
(The exception being that the Windows OS you are running is counterfeit or indeed infected in some manner. Make it look like Defender is the cause and people will, as you did, start removing Defender. And things get worse thereafter.)
Especially destroying a print head ?
But I found a reference to that:
https://www.digitaltrends.com/computing/alt-tab-broken-windows-10-update-how-to-fix/
From the link:
"An update released on August 10 (
KB5005033) should have solved the issue, but it didn’t. This update is of particular concern because it’s mandatory, unlike the optional July update. The second update
includes security updates to Microsoft’s ongoing issues with the
PrintNightmare vulnerability, so you should install it regardless of it breaks
Alt + Tab or not.
View your update history for missing or problem updates.
However I still do not understand how that vulnerability could physically destroy a print head.....
= = = =
This:
"All of my Personal computers that i ever had, done this little annoying thing after a while, for decades, some from the very first day. "
Another thought is that you are running some tool or app that is the source of the problem. That is the only constant that I can see. Something you immediately do on each computer. Maybe install a favorite tool, utility, game, or other app.
For whatever reason that software generates or otherwise sends out Alt-tab. May be the result of reprogrammed/reassigned key functions - perhaps in a game.
What you can do:
Look in Reliability History and Event Viewer for error codes, warnings, or even informational events that are captured just before or at 0:00 time.
Look in Task Manager for any unexpected or unidentified software being launched at startup and running in the background.
Look in Task Scheduler for any tasks being triggered at 0:00.
Let Windows do some cleaning up on its own via "sfc /scannow" and "dism".
References:
https://www.lifewire.com/how-to-use-sfc-scannow-to-repair-windows-system-files-2626161
https://www.windowscentral.com/how-use-dism-command-line-utility-repair-windows-10-image
And that it happens at 0:00 makes me think about the system time. Where does the computer gets its' time and does the computer do some synchronization(s) or other taskings at 0:00?