A domain user can have time restrictions on their account use in their
account properties in Active Directory Users and Computers. On a non domain
computer you can use the "net user" [net user username /times:]command to
also time restict a user account. However it may not work on a user already
logged on, though there is an security option for domain accounts to force a
user to disconnect from domain resources [however it will not log them off
of their machine locally]. Another machine specific option may be to use
scheduled tasks to force a logoff at a certain time via the logoff command
which in conjunction with user account time restrictions could keep them
from logging back on until appropriate time. --- Steve
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechn
ol/windowsserver2003/proddocs/entserver/net_user.asp
http://tinyurl.com/v1hb