My 3 boys have a comp with Vista Home- none of their account are password protected- but have parental controls set up.
Can I lock the computer from all their use using my admin passwod?
within Parental Controls you have an option to set the allowed log-in times if you set them all to never they won't be able to log-in, is that what you want?
the Ctrl-Alt-Del method will only lock them out of the one account - yours.
they can always use switch user from the lock screen to log back in to their own account. or they could just switch off at the power socket and reboot to the log-in screen
the only way to keep them locked out is by setting a password on the BIOS to stop the PC even booting without it's entry. most BIOS's have this facility to protect the settings screen and most will also have the boot password option.
hope this helps
Pressing DEL at booting will usually get you to the BIOS and there should be an option to set up a password.
I am curious to know why you want to do this, if because you don't want them to use it, why don't you just disconected all together or forbid them to use it?