Background: if you don’t want others to enter or start your own computer, then there’re lots of methods, but it’s also quite easy to crack them. This case also has a crack, but I just provide you some idea which may bring you an unimaginable effect.
Principle:'Camouflage'—encrypt by using commands 'Choice'  (waiting to enter one character) and “Echo” (display error message).
Coding: open up with notepad or create a file Autoexec.bat, and type the next content:
@echo oFF
echo non-system disk or disk error
choice /c:#/n
Usage: “non-system disk or disk error” is displayed when start, which causes system down. You may surprise once take a look. If it starts by itself, then you could type “#” at leisure (equal to the start password, don’t type the quotation marks, same as the next one), then the computer would keep running until enter the desktop.
Frighten away invalid visitors
Background: if you don’t think the example above is useful enough, then you may try this one.
Pricinple: with Echo command to let it display 80 “_” each row (80 underlines), and then use Goto command to set a dead cycle application, finally reaching the effect “Blurred screen”.
Coding: open up notepad and create C:＼windows＼winstart.bat, and type the next content:
@echo off
:abc
echo_　//“_” is an underline in English，please enter 80 “_” which is the only to reach the effect.
goto abc