Upon automatically installing updates, Windows will reboot your computer without your consent, losing any unsaved work in the process.

Automatic updates are usually a good thing but there is a serious problem with it.

Sometimes updates need to restart the computer to finish the installation. Until SP2 Automatic Updates would not restart your computer automatically. But this is not the case with SP2.

This behavior can cause a lot of problems. Documents you left open and did not save will be lost, downloads you started that have not finished will be terminated, and even hard disk maintenance like defrag that is working will get terminated, which might cause lost of data.

Unfortunately Windows XP Home users can not do much to change this behavior, except saving all the data before going to sleep or disabling the automatic updates.

On the other hand Windows XP Pro users can tell Windows never to restart the computer automatically.

The next time Windows updates your system it will not restart the computer automatically, but will notify you that restart is needed in order to finish the installation.