Scenario 5: The Computer restarts over and over

Both Windows XP and Windows Vista by default restart if they encounter a system crash. So the first thing to do in troubleshooting this problem is disable the automatic restart on system failure.

To do this, press F8 during startup (you might have to press it multiple times to get into the menu) You will enter the safe mode menu.

In the menu, select "Disable Automatic Restart on System Failure"

This option specifies that the computer will not automatically restart whenever the system unexpectedly stops. Use this option to keep your system from restarting while you troubleshoot system failures.

You will then see an error message or blue screen, see scenario 4.

More information on the safe mode menu can be found here.