>I am sure I have seen someone post an API call that prevented a user from using ctrl-alt-del to reboot the system. Can anyone point me to this?

Not directly AFAIK, since Ctrl-Alt-Del under Win9x/NT fires up Task Manager (Win9x) or the NT Security Options selector. You could intercept the call, but there are too many things besides rebooting associated with the three finger salute to completely disallow the keystroke.

Under NT, you can restrict the user from shutting down NT pretty easily; simply remove the user from any group having the 'Shut down the system' right in User Manager. Under Win95, you may be able to restrict this through the Policy Editor if user profiles are in use with ZAK, but I've never tried to do this.