How to Lock your desktop
If you are leaving your computer for a while and do not wish to turn it off,
but want to assure that no-one else can use the computer while you are
away, locking the desktop is the best option.
By pressing WINDOWS KEY+L, you password protect your system just as if
you had logged out or restarted the computer. The advantage is that any
programs or processes that were runningwhen you locked the desktop
will stay open and running in the background, ready for you to resume
work or play.