My computer randomly shuts off. When I turn the computer on, it turns off again before the password screen appears. It will continue to shut off whenever I turn it back on.

I downloaded IE 7 and MADE some updates on my Norton and ever since then I have had this problem.

Also, the computer shuts off when I run a full system scan.

Does anyone have any advise?So you can't start the computer at all?
Have you tried Safe Mode?
I presume this is XP as you have IE7 - what service pack? Home or Pro? Is it genuine?Yes good point, you should try SAFEMODE and then do a system restore (if it will LET you). Or you could put in the restore cd (WinXP cd) and start the recovery console, or (recovery disk) depending on the model of your computer or if it was home built.Once the computer turns off, I can turn it back on. But literally 20 seconds later it turns off again. This happens every time I will try to turn it back on. I would have to wait a couple of hours before the computer will turn on and STAY on.

I am using XP home edition.

My computer is a Toshiba SatelliteSounds like a heat problem.
Are the vents CLEAR, does the fan spin when you turn it on?
Are you using it on a hard flat surface?