My PC shutsdown by itself

hi there,
my pc started to shutdown by itself about two days ago..
it's a self-built with Intel Core2Quad Q6600, 4 GB Kingston 800 MHz RAM, nVIDIA 8500 GT, 320 GB WD SATA HDD, and ASUS P5K MB

i don't know the reason, but the night before it happened i detached the fan to clean it then re-attached it again "appropiately" and turned the pc on and it worked, and i did a deep system scan using trail version of BitDefender Total Security 2009 "which ends tomorrow btw" and i slept, and when i woke up the next day it was done and i read the report and all was good!
i turned it off, and by noon when i started it again, the problem appeared, and it started shuttingdown by itself since then..
i am writing this post while i am on SafeMode, and it's working on safemode and didn't shutdown in half an hour now.,

am done, and if you need any further info, just ask
waiting for a reply soon.,


thanks, guys

Firstly, do you have any apps that have a "shut down computer when finished" option? ie a torrent client, disc burning, DVD encoding etc

Which fan did you disconnect? CPU, case fan etc

Was the computer idle, or under load (games etc) when it shut down?

ok,
- i don't have any apps with "shutdown after finishing" selected
- i disconnected processor fan
- the computer shutsdown once started, after a min or two as max
- note that after i re-attached the fan the computer worked for a whole night scanning and i woke up the next morning and it was still on

waiting...

If it's shutting down after a min or two, then it sounds like a heat issue.

It maybe worthwhile to download an app like speedfan or realtemp to check what temps the CPU is currently at and what speed the CPU fan is running at:
SpeedFan - Access temperature sensor in your computer

In your BIOS, you should also have a CPU temp and Fan RPM monitoring. It may be worthwhile checking there as well.

i have ASUS PC Probe II installed as part of ASUS MB CD, it shows no signs of heat..
i had that thought, too. so i turned on an external fan right above the MB and processor, so it can't be heat problem...

could it be a virus?! i really doubt that, cause when i log in to SafeMode it works fine, i am already on it for an hour or more.,

btw, the computer shutsdown right after opening, which leaves me no space even to open IE..

i am writing to you from SafeMode!!

The Asus PC Probe isn't particularly reliable. Also, if it were a heat problem, then safe mode would probably be affected too.

When you say it shuts down, is it a complete shut down (pc turns off and stays off) or does the PC restart again?

And this only occurs when booting normally?

Did you apply any updates, install any new apps ?

it's a total and complete shutdown, like when you cut power source..
and yes, it occurs only when normally booting, it works fine in safemode..
and about new apps, i don't think so, but i connected a friend's HD to my pc the same night before it happened, so i guess it might be a virus, cause his pc had the same problem before!

At what stage does the PC shut down? ie during the loading bar, just after desktop.

Do any dialogue boxes pop up just before shutdown?

You could try looking at the startup list in Msconfig for any suspicious entries (press WIN+R to open the run command, type "msconfig" and check the start up tab.

Alternatively open regedit and check the run keys for any suspicious entries (press WIN+R to open the run command, type "regedit" and navigate to:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

Is your friends HD still attached?

the shutdown happens right after desktop appears, i can have time just to open "My Computer" only, for example.. it's like 30 secs to 1 min after desktop appears

no dialogue boxes appear, it just shutsdown

about suspecious entries, there are two values (one in HKEY_LOCAL_MACHINE and the other in HKEY_CURRENT_USER) i don't know if they're suspecious or not, they are:
name: (Default), type: REG_SZ, data: (value not set)

finally about my friend's HD, i just connected it, formatted a drive for him, and disconnected rigth away.. it was for about 15 mins...

Those reg entires of (Default), type: REG_SZ, data: (value not set), just show that they are empty. It's odd that there is nothing in either though :huh:

If you didn't execute any files / copy any files from your friends HD, then the chance of infection is low. However it might be worthwhile trying another A/V scan.

A couple of good free A/V to try:
Download anti virus for Linux and Windows, anti spam, recovery software tools
Download FREE antivirus software - avast! Home Edition

And a malware scan:
Malwarebytes.org

The fact that the PC does not shut down during safe mode tends to rule out hardware. Even though bitdefender scanned clean, it can't hurt to run another scan with a different product/s.

If an infection is ruled out, then obviously it's time to look elsewhere.

you should mean to run it on another pc, otherwise it won't be applicable, cause windows opens for like 1 min, and bitdefender doesn't open in safemode..

anyways, i'll try to run it anyhow.,

forgot to tell you, when the scan was done, the report showed there was an infected file and it was removed or disinfected, don't remember..

Bitdefender should have a log somewhere that will tell you which file was infected and removed.

It may be worth running SFC to check the integrity of your files and possibly replace the file if it was a system file:
http://www.vistax64.com/tutorials/66978-system-files-sfc-command.html?ltr=S

im having simalla issue with mine and its when im on msn or playing sof2 or sometimes not even that and its not overheating in fact dont think its hardware as all parts pretty new and wasnt doing this before its geting more frequant and software anti v's are not picking it up if it is a virus

any ideas other than all described here as i have tryed including the run keys and any more info you may need reply and i will respond back thanks also no other games seem to affect this pc other than this 1 game solders of fortune 2 double helix silver

i tryed out mouse trap (bad idea messed ma sof2 up) im thinking its linked but how can i fix so i can play sof2 or just prevent shutting of my vista down by itself.

i have tryed xp and does same if not worse so whent back to vista


also these issues started back after i tryed using ms windows xp from a old version and i went back to vista and problem remains any ideas (i am looking to try to use a unused hdd but am waiting for delivery before this option is available to me).