automated shutdown

Sounds easy by the topic, but it is not an easy problem. Our district is looking to trim costs off of the utilities budget. I know in advance that I can use MCX Policy in Workgroup Manager to set an automatic shutdown at a given time each day. Sadly, I can only schedule at one time each day using the GUI tools. We have been handed down for the powers that be that all machines will need to shutdown at 6 p.m. For those users that turn the machines on after the 6 p.m. shutdown, they will receive another one scheduled for 8 p.m. This will happen every two hours until 6 a.m. the next morning. Unfortunately, Workgroup Manager using the GUI tools can only assign one shutdown time to a single computer group. I also wish to block the user from canceling automatic shutdowns (we don't mind if they are warned though and are given a few minutes to save documents and whatnot). The Windows admins are able to implement this using third-party software. My boss is open to third-party software suggestions, but I figure I might check here first. My solution ideas right now go in two directions: 1. Create multiple computer groups, each with a different shutdown time and assign a given set of machines to it. (I am going to test this route tomorrow, but do not hold much hope for it considering I would be forcing 6 totally different energy saver to each single machine...likely not going to work according to Apple, but they suggested I try.) 2. Right a cron script/launchd job to that effect. This method seems hopeful except I run into two problems....a.) proper syntax for a scheduled shutdown command that it runs every two hours from 6 p.m. to 6 a.m. the next morning. b.) how to make it display a warning message to the users 10 minutes ahead of the shutdown that they will see in the GUI. I know the following command works, but assumes the user on a workstation has the terminal open...I want them to get a GUI warning if possible: shutdown -h +10 “Warning text here” Hopefully this is specific enough and I can probably answer questions to those who may ask. I thank anyone for help in advance Brian Martin Lafayette School Corporation (K-12) Lafayette, IN