Windows 10 deleted this computer’s anti virus software
According to the message that popped up, the AV software that was installed was incompatible and so Windows 10 disabled it and activated Windows Defender.
When I checked, it had actually deleted the software entirely. I installed Malwarebytes to clean up the machine, which you can see in action in the video. In total it found 2639 threats.
So this is a warning for Windows 10 users. Do not assume everything is fine.