Again Halt as user

[cristian]

Ladies and Gentelmen,

I did everything you said.
I added /sbin to user's PATH.
I tried /sbin/halt or  ./halt.

I got only one result: the message "must be superuser".

One thing worked: su ,  but it is asking the root password.

As a matter of fact I am using my box as a home-PC. I am the superuser
and the kids are users, and I don't want give them the root password.
But they need to shutdown the computer. I don't use the computer 24h/day

How can I solve this?

Thanks.

Cristian Carnutu