We get variations of what is essentially the same question all the time: the system doesn't start Windows, dropping to PXE boot and failing and/or throwing a "no bootable device" or similar error. The answer is the same nearly every time. We ought to collect all these questions and have one question to rule them all.

In the spirit of this earlier Meta question, I've posted a new canonical question aiming to cover all these cases. I intend to close all other questions of this kind as duplicates of this canonical question. Please post any feedback here.