Computer shutdown by NT AUTHORITY/SYSTEM

[drragostea]

My machine was suffering from lags and some lockups; it occurred just that one time. Firefox would initiate but the window would not open.

The PC shut down by "NT AUTHORITY/SYSTEM" prompt; so I had no control over what occurred. I did remove PC Tool's Threatfire because I had a nudge that may have been the problem.

At the moment the computer is running normally; a screenshot is attached.
Does anybody have an idea on why this would occur?

[shelf life]

Many years ago some worms used the vulnerability as a means to compromise (http://www.securiteam.com/windowsntfocus/5SP0C20AKG.html) machines. Its long been patched (http://support.microsoft.com/kb/826955) by MS. No doubt you are up to date with Windows and your virus definitions. This is what comes to mind first for me anyway. I wouldnt worry about it unless it happens again. If you use XP Pro you may find some clues in event viewer.

[drragostea]

Yes, my machine is patched. Thank you.

shelf life, are you familiar with Comodo's Firewall?
I had a prompt once that told me about explorer.exe associating with some potential buffer overflow attack; I ignored it on purpose because the last time I terminated explorer.exe, I could not log on to Windows afterward.

[shelf life]

No I am not familiar with Comodo's firewall. Some software firewalls and there associated components like host based intrusion protection systems (HIPS) can put up some complex questions or decisions a user must make on the fly. Really, the user behind the keyboard is still the driver. You might dig up some info about it at the Comodo users forum.

[drragostea]

Thanks for the confirmation.