Making sure your Windows system is OK...

If you have Windows 8 or Windows 8.1 you can run this command using your Administrator privileges, to confirm that the system is complete and healthy. This also works in Windows 7, but without the "/RestoreHealth" option, because this program was slightly different back then. You can confirm all this by also running the old reliable "SFC /scannow". But DISM will tell you if your system conforms to the installation image, and can restore that for you. This is faster than re-installing Windows, and preserves all your files.

Please note: This does not work in Windows Technical Preview. It will try, but it will tell you it was unable to complete it. 

And another nice thing about DISM is that you don't have to re-install any updates afterward, as you would if you did a Windows re-install.

Here's what happens if I try to run these tools in Windows Technical Preview...