Manny,
It is possible your friend has their computer to automatically restart on a
BSOD which in turn could be caused by a software failure.

"Dan H" <someone@nospam.com> wrote in message
news:eF3C#W28JHA.1492@TK2MSFTNGP03.phx.gbl...[color=blue]
> In most cases it is either like mentioned Dirt causing overheating or bad
> power supply. As suggested clean out your computer. If it still reboots
> after cleaning it out you likely have a bad power supply.
>
> "Manny Weisbord" <mannyweisbord@crimest.invalid> wrote in message
> news:3nct35pje23gut33rt3cbquls1oqm1nohc@4ax.com...[color=green]
>> [crossposted to microsoft.public.windowsxp.general]
>>
>> Kristoffer <guest@unknown-email.com> wrote:
>>[color=darkred]
>>>
>>>Hello! I just wanted to ask why this is, a friend of mine has a
>>>computer, its not vista doubt. It just Windows XP. So, it shuts down
>>>without any error or anything, I mean like your surfing on the web and
>>>the computer shutsdown and restarts, what can the issue with this be? I
>>>mean, it just turns off, without any warning, It turns pitchblack and
>>>the computer turns on agian. I helpt him defregmantating his computer
>>>multiple times, but it still dosnt work.
>>>Sorry for my bad english![/color]
>>
>> 1) More info is needed about the situation
>>
>> 2) Post your question to an XP group... this is for Vista.
>> (I've taken care of that for you)[/color]
>
>[/color]