I didn't read all the posts here, so not sure if you have considered this: Windows 98 has a serious shutdown bug and MS has a long-ass document on how to troubleshoot, which in 9 times out of 10 (or more), it doesn't work. The solution? Upgrade to Windows NT or 2000. Sounds like a smart-ass way, but you'll find that I'm right. I spent hours and hours researching this a couple of years ago, and you'll NEVER find a fix. Just thought I'd save you hair. I am now bald.

Later. Good luck. Don't waste any more time. If users complain, just tell them to hold the power button in a few seconds, it will shut down. Sorry, just the facts.