[mothered]

Perhaps it's also a viable option to run the entire computer under a sandbox so that any changes made to the computer will be reset each reboot, something that would be used in a school environment. One that I've encountered is called "Deep Freeze"

In my experience, Deep Freeze works very well In rolling back to It's previous state after reboots.

As you mentioned (and as I've also experienced only a couple of times), It's not 100% fail-safe, but certainly worthy of Installing.