Open Control Panel, open System, go to the Advanced tab, click Settings
under Startup and Recovery, remove the check from Automatically Restart
under System Failure, click ok. This should force the system to stop at the
blue screen which may give you a clue as to the source of the error.
Other things to check if the above doesn't reveal anything to you:
Be sure your antivirus software has the latest definitions and run a
virus scan.
Download, install and run Ad Aware:
www.lavasoftusa.com
Note: you should always be well backed up before running an application of
this type.
Open Control Panel, open Administrative Tools, open Event Viewer, look for
errors corresponding to the crash, double click the error, the information
contained within may give a clue as to the
source of the problem.
Assuming you have an XP CD and not a recovery CD, place the XP CD in the
drive, when the setup screen appears, select "Check System Compatibility,"
the report it generates may point to problem hardware or software on your
system. If you do not have an XP CD, you can download this application
known as the Upgrade Advisor from the following site:
http://www.microsoft.com/windowsxp/pro/howtobuy/upgrading/advisor.asp
Note: If you have access to a broadband connection it might be best to
download using that as this is a rather large download.
Check for the latest drivers for your hardware, especially your graphics
card and soundcard and all peripherals connected to your system. No not use
Windows Update for this, go to the device manufacturer's web sites and if
you install updated drivers, ignore the message about drivers being unsigned
by Microsoft.
If none of the above helps with this shutdown issue, please try the
following website:
http://www.aumha.org/a/shtdwnxp.htm