As a general rule it is best to sit at your chair and when you wheel it towards the computer to start your session, you should first touch the metal keyboard tray or the desk itself BEFORE touching the keyboard or mouse, to prevent the static discharge.
Welcome to the world of windows!! You can quite easily get a static discharge from an office chair to the keyboard which could result in a frozen keyboard.. pressing and holding the power button until it restarts, or if the desktop has a reset button, usually just above or below the normal power button, then you can use this as well.
