Your computer may reboot for no apparent reason, and without any prior warning.

This is the default behavior when Windows XP encounters a System failure. This behavior can be changed by going to the System applet in Control Panel, select the Advanced tab and click the Settings button under the Startup and Recovery heading. Under System failure, un-check Automatically restart (see picture 1).

Picture 1

To check why your system had a failure, check the Event logs for any error messages. You can find the Event Viewer in the Administrative Tools, or by typing eventvwr in the Open box from the Run command.