Reset Windows 7 computer to a clean state on reboot
Solution 1:
Microsoft use to have a tool called "Steady State" to meet just this need. While it no longer works under Windows 7, Microsoft has an official write-up on how to accomplish the same thing using native Windows 7 features and free tools.
This write-up is available directly from Microsoft at https://technet.microsoft.com/library/gg176676.aspx. The Overview is provided here:
Windows SteadyState does not support Windows 7; however, many of its features can be replicated by using native Windows 7 features and free tools from Microsoft. This document is intended primarily for IT pros who configure shared-computer access in business environments, but partners who support shared-computer access in schools, libraries, and Internet cafes will also find the information useful. The document set includes:
Creating a Steady State by Using Microsoft Technologies (this document), which describes the native Windows 7 features and free tools from Microsoft that you can use to create a steady state on computers running Windows 7.
Group Policy Settings for Creating a Steady State, which is a reference that describes Group Policy settings that you can use to configure computer and user settings and prevent users from changing those settings.
The SteadyState Reference worksheet (.xlsx file), which you can use to look up and filter settings that this document and the reference describe. For example, you can quickly find information about settings that are related to Start Menu restrictions.
Solution 2:
You can use something like Deep Freeze to keep the configuration consistent or you can just re-deploy images nightly with WDS and some BIOS configuration settings.
Solution 3:
For remote computers like this, you may be best served by using Windows Embedded / Thin PC. This has a facility called Enhanced Write Filter which effectively turns all writes to a specified drive into writes to a ram disk. Although while Windows is running, it looks like the drive contents have changed, in reality it hasn't. When you restart windows the contents of that drive are exactly the same as when you turned on the EWF,
We used to use this with an embedded vision PC which could lose power at any time. We set EWF on the boot drive and left another drive writable for storing images. Nothing that happened could cause the boot drive to be written to, so it was pretty much guaranteed to always be able to boot.
The big advantage of EWF over cloning is that you will never have to wait for your clone to complete before restarting.