Copied from a recent Yahoo article:
Tip 1: Automatically log when and why shutdowns have occurred.
Love it or hate it, Windows XP is undeniably more stable than its
predecessors. But it still crashes, and it still has occasional trouble
shutting down. This registry hack logs all shutdown errors, telling you
when, where, and why strange and annoying things have happened.
Some folks have the luxury of packing their buggy PC off to a help
desk. But if you like to get your hands dirty, consider this essential
tweakage.
Here's how to set up logging for unexpected system shutdowns:
1. Open RegEdit and browse to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
Reliability
2. Set the ShutDownReasonUI data value to 1. (If this string doesn't
exist, create it and set the value to 1.)
3. Exit RegEdit and reboot your PC.
To examine the log you've created, open up the Event Viewer, which
you'll find by selecting Control Panel > Administrative Tools > Event
Viewer. Click on the System subheading and you'll see a massive list of
system events. Errors will be marked with a red X or a yellow
exclamation mark. Double-click on the error and you'll see details that
may help you unravel the mystery.
