I have used Deepfreeze for years. A very good program that I use in a classroom environment. It prevents students from doing any permanent harm to a computer. What the program does (when installed) is take a snapshot of your system. When running in the frozen mode anyone can hack the OS, delete files etc and it is all transparent. Simply reboot the computer and it loads from the snapshot and any changes made while frozen are gone.
Having said that it should be obvious that if you are using this program on a computer where you value your data, be prepared to lose that data. If for instance you get an email while frozen, that email will be gone on the next reboot. Same for any other data created while frozen. This is not a program to be used on your home computer as you will end up losing data. It is a program that can be used where data is not a problem and you do not want to spend hours trying to figure out what the student did to this computer. Simply reboot.
As stated above it is a very good program but be careful of the application.
