Windows Restart without Warning

This issue could be caused by any of the below possibilities.

Software issue or error.
Hardware issue or error.
Heat related issue.
Computer virus.
Issue with operating system.

With the introduction of Windows XP Microsoft designed Windows to automatically reboot each time an error occurs such as a BSoD. Although this may be nice for errors that do not occur often, users who have a re-occurring error may wish to identify the error to troubleshoot it. Below are the steps on how this feature can be disabled and enabled in Windows XP, Vista, 7, and 8.

This document is for computers that are restarting or rebooting by themselves and not computer's that turn off and remain off.

Cause

This issue could be caused by any of the below possibilities.

Software issue or error.
Hardware issue or error.
Heat related issue.
Computer virus.
Issue with operating system.