Hi, do you know? You can lock your desktop picture on your PC! It means, however your PC is easily accesible by your friends or other people, they can't change your desktop picture, except yourself! Wanna know more?
(THESE STEPS BELOW IS JUST FOR THE USERS OF "WINDOWS XP")
Make sure you know the password to your computer.
Press Ctrl+Alt+Del on your keyboard.
Choose "Lock Desktop."
Your computer will be locked immediately.
If you need access to your desktop again, press Ctrl+Alt+Del.
Enter your password and you will then be able to resume activity on the computer.
It's very simple...!!! Want to do try it right now..??? ^^