Any error message?
Please change this setting in order to receive error messages:
Turn off Auto Restart in order to get error messages:
Right click My Computer then click Properties > Advanced > Startup and Recovery > Settings
Unclick Automatically Restart under System Failure.
This should freeze your screen on an error message.
Also:
Look in your Event viewer: rt. click My Computer then click Manage then Event Viewer.
Or: Administrative Tools/Event Viewer or Start/Run/ eventvwr
Open the system as well as the application tabs & look for red
X errors. Click error line for details.
Post back the source & event id & Description especially of errors that seem to coincide with this issue.
Also check the Information lines that might coincide with this issue.
How to view and manage event logs in Event Viewer in Windows XP
