I ran into the most annoying (understatement) thing about certain Microsoft automatic updates (on Windows XP Pro). It seems that last Tuesday was yet another 'patch-Tuesday'. Nothing unexpected about that, but this update (or at least one of them) required a reboot of the PC (yet, still nothing wrong with that).
Normally, the automatic update process bugs you about rebooting, but somehow this reboot interface had a timer. A timer of 5 minutes. After these 5 minutes the PC will reboot.
Totally ignorant to open (modified) documents. The shutdown process kills all open programs / documents and reboots. Without waiting for user input on e.g. saving files.
I tested this with opening a notepad document, altering it and leaving it open. After 7 minutes, the PC had rebooted, and all changes to the document were lost.
Yet another 'Thank You, Microsoft'