System Silencer is a freeware Windows program which triggers any of a bunch of automatic actions when it senses that your computer is in idle mode, say if you leave your seat to go buy a burger. You can set it up to switch off the monitor, lock the system or even run a particular program and you can set the ideal idle timeout as required. Nice and simple.
Run System Silencer and when you’re away your computer’s monitor can turn itself off, the sound will be muted and you can even choose to hide your taskbar and desktop icons! Of course, you can skip all the hiding and just configure System Silencer to lock your computer while you’re away. Additional options allow you to kill a process and run a program or file, if you have anything specific you’d like to hide or show while you’re “afk”.