Instant restoration after reboot

Hej

Er der nogen som kender et alternativ til dette:
http://powershadowsecurity.com/PowershadowProducts.aspx

Programmet gør det muligt at alle ændringer til harddisken bliver slettet efter en reboot.. Jeg leder efter noget opensource eller andet som kunne være gratis, men som indeholder den funktion.
Ex.

When you let others use your computer, place it in ShadowMode before they start to use the system. Then, when they are done, you can simply switch back to normal operating mode and any changes that they made are gone. In a classroom or lab environment, simply reboot the computer back into normal mode after each student and all changes made by the prior student are discarded and never reach the hard drive. This saves a lengthy restore of the hard drive from a backup file after each class or user.