My first inclination would be to tell your friend to check for
updated video drivers on the manufacturer's web site. If that
doesn't help you might want to tell your friend to do the
following:
Start -> Control Panel -> System.
Click on the Advanced page.
In the Startup and Recovery section click on Settings.
In the System Failure box remove the check mark next to
"Automatically Restart".
Now, when your friend selects log off or stand by, a blue screen
should appear that might give a hint as to why this behavior is
happening. Also, look in Event Viewer for any entries that
coincide with the reboots. Record the important info and post
your question to an XP newsgroup that has a more appropriate
focus. As you're using the web interface, look under
Windows/General Discussions for the General and "Help and
Support" newsgroups.
