I work in an area of Wisconsin that suffers from frequent power outages. In my working environment, I have two Windows 2000 Server machines. Each machine is connected to an APC Smart-UPS battery backup unit and runs APC's PowerChute Business Edition software, a UPS management and shutdown program. After I installed the Security Update for Windows 2000 (KB841533) hotfix on both servers, they started experiencing random dirty shutdowns during power outages. Because I wasn't having any abnormal shutdowns prior to the KB841533 hotfix installation, I began to believe that the files installed from this hotfix might be causing the problem.
However, while I was trying to figure out how to stop these dirty shutdowns, I came across the Microsoft article "You may experience an abnormal shutdown of your Windows 2000 Server-based computer after the Windows logon screen saver starts" (http://support.microsoft.com/?kbid=883635). The article mentions that you can experience an abnormal shutdown when the Windows logon screen saver starts and a UPS program calls the ExitWindowsEx function. The article also describes the same event message—The previous system shutdown at <time> on <date> was unexpected (event ID 6008)—that I kept observing in my system event log. After a few simulated power outage tests, I realized that this article was describing the problem that my servers were experiencing.
Fortunately, there's a hotfix that corrects the dirty shutdown problem. However, it truly surprises me that Microsoft hasn't aggressively publicized this hotfix. I know many IT people who would be shocked to find out that their battery backup software might not shut down their servers correctly, even though they've taken the time to configure the software properly.