Tough virus, shuts pc down at hint of detection!

I know that a computer in my household has been infected with a virus, and it seems to be shutting down the computer at times.

Just then i was about 30% through an Avira virus scan, and the thing just turned off, much like when a faulty power supply is at fault.

When i turned it on, it just shut down at the windows startup screen.

The computer seems to be infected whilst in safe mode too, as even when i try to select safe mode from the startup options the thing will shutdown.

Now, the symptoms from last night, when i was aware of an infection, but it did not shutdown at the time:

Windows logon names would not be "clickable", i.e. when pc was on, you could not click on your name to logon.

The usual painful slowness associated with virii

Being able to click on your name, but it hanging on the desktop.

I really want to avoid a clean re install.

So far i have tried the following,

Avira
Hijackthis
Malwarebytes (does not start – probably due to virus)
Superantispyware (Same as MBAM)
AVG 8
Ad aware

And was about to try dr web curit, but seems pointless as the thing seems to turn itself off at the hint of virus detection.

 

I prefer to use Hijackthis.de

 

You can try Dr.WEB LiveCD, it's good for unbootable systems like yours

 

I wonder if ESET SysInspector would be of any help in identifying what malware is on your system?http://www.eset.com/download/sysinspector.php

 

Try Avast!

It has boot-up scanning which might be able to catch those nasties before system start-up.

Also, use ComboFix and SDFix.
ComboFix can be put in a flash drive, but after 30 days, it's features will be limited.

 

How u know that it,a a virus/ malware etc?
Why not a corrupted/ damaged OS itself? To me this one is more likely.

I will suggest to do a repair install of windows and then run some AV, AS scanners.

 

When the pc Shutsdown,Is there any message such as been shutdown By NT authority,If yes then likely your are infected.Aigle may be correct also try a repair installation if you have windows CD or have you even tried a simple system restore before it shuts down and then scan after words,but the infection maybe in the restore area as well.If you use DSL or cable I would also suggest disconnect from any internet access for the time being while trying to clean it.I Also would make some bootable options such as DrWeb live CD from another PC or have someone make you one wouldn't hurt.If its not a corrrupt OS or hardware failure and all else fails why not just formatt and be done.Just for future reference look to image recovery solutions.

 

Heat issue. Are all fans, vents, heat sinks open, free of hair, dust, and running?

 

Is it shutting down "properly" or as if the cable was pulled out?