I think this is for a busy environment, with busy/distracted people using the computer.

It has to "not work" when they walk away.

Bruce,

Stopping the cpu in midstream doesn't sound like a very good idea.
Especially with Windows.

Could be writing to disk or whatever at the time.

Just a thought ... You could simulate pressing the sleep button on a keyboard, to let the system enter stand-by when it doesn't see a badge. Then limit Mouse/Keyboard activity until it sees a badge again.

But that sounds difficult.

_