By default, Windows XP is set to restart on error. To stop the restart, sometimes just a simple operation, but it is not effective in all cases:
1) Go to the Start menu, then Control Panel then Performance and Maintenance and then System (or by right-clicking on “My Computer” and selecting properties)
2) Click the “Advanced” tab
3) Click Settings in Startup and Recovery
4) Uncheck “Automatically restart”
Open the System log of Event Viewer
You can read the error messages or system generated by the event viewer. To get there:
1) Open the Control Panel, then Administrative Tools.
2) Double-click on Computer Management
3) Open the Event Viewer (under System Tools) and read the error messages.
Just then do a search on Google with the words and the error codes most relevant error message to find people having the same problem, and possibly the answer to the question!