While Microsoft's Steady State was worth noting, DEEP FREEZE appears to be what you are looking for.

BEWARE THAT SOME DO THIS BEFORE THEY FIGURE OUT THEY DIDN"T WANT THIS ON THEIR MACHINE.

Also this is not a sure fire way to accomplish your goal. For example I use a bootable USB stick when I encounter such a machine to show a flaw they often miss. Remember that these are PCs and not terminals. But that doesn't mean folk won't stop trying to turn them into terminals.
Bob