sleep password


I have 2 accounts on my computer and I have it set up so that it goes to sleep after 10 minutes but when it does if the last person on the computer doesnt log out it doesnt go back to the main log in screen.You have to know the last persons password and log them off first and if there not around I cant use the computer.If I set my screen saver to never come on my computer will not goto sleep at all even if I have it set up to shut the computer and hard drive off in 10 minutes nothing happens.