How do I do a Full Shutdown of my computer?
When you press shut down, Windows doesn't actually fully shut down. It puts itself in a state of hibernation so that next time you boot up, it starts faster. This can cause some problems that may be able to be restored by fully shutting down the system.
While shutting down (see, How do I shut down my computer?), hold the SHIFT key.
Restarting will also perform a full shutdown, but it reboots itself afterwards. If you want to fully shut down your computer without it turning on again afterwards, this is how you do it.