..access to task manager is also impossible.
This is always a bad sign, and indicates either registry tampering, or a malware process running. If the latter, then unless you can stop the process first you are
completely wasting your time trying to do anything else.
IMHO you need to tackle this from outside the compromised OS. You need a bootable CD, such as BartPE, Knoppix, or (my preference) UBCDWin and a portable virus-scanner. I generally use ClamWin from
http://portableapps.com but any competent scanner which doesn't need installing will serve. Avast is probably an option, just not tried it yet in that scenario. Anyone have experience here?
The other point is that if you keep the computer connected to get virus updates, it might be pumping-out spam all of this time. So, best disconnect the LAN/Internet cable until you have it running a clean, LiveCD OS. You can then update the scanner's defs, scan, and upload any suspect files to
http://virustotal.com for confirmation.
That said, you have to remember that a lot of new malware downloads additional malware whilst running, so you may be dealing-with several infections, plus some 'dropper' files which might not be detected. If faced with this situation, the best answer is to 'bite the bullet' and erase the entire disk, -again from a bootable CD, NOT from within the infected OS. Alternatively, if the data is worth more than the hardware, just buy a new disk and get the computer running with this. You can always sort-out the infected one later -being careful of course not to risk a re-infection.
Hope this general advice helps.
