For systems builders, few things are as frustrating as a system that has crashed and just won't boot up again. The so-called Blue Screen of Death stares back at you mockingly, adding insult to injury.

This post features solutions to fix An operating system wasn’t found error in Windows 11/10. This error prevents your Windows device from booting up properly ...

EDIT: It did - changing that setting back to "AHCI" resulted in a, "This operating system failed to start", message when I tried to boot XP. Changing the BIOS back to the "IDE" setting didn't fix that ...