Thanks a lot for your responses. The recommended website was great, but I still cannot find any Trojans and viruses.
-I did not have any Anti-Virus software on my PC before the break down of my PC and the replacement of the Hard Disk. (long story, how I know the exact day of the start of the attack).
-According to David R , my PC has been reinfected again. Very likely by visiting the same suspicious weblog, wherefrom - I'm sure now- I was attacked in the first place. (long story)
-The attacker contacted me 2 days ago by icq (I was 100% sure it was him). The moment I clicked on the message, my sniffer showed no more suspicious activities, but instead I could see on "SENT"-Internet-traffic-monitor, that the person, through icq window/contact, is directly sucking massive amount of data periodically(again about each 5 minutes) .
- Are such icq numbers (from which the attacker can attack the PC directly) also proxies and cannot be tracked? could the ICQ number lead to the PC address of the attacker?
-I receive recently every once in a while, a very suspicious-looking blue window on lower right side of my desktop, which says: "Avast Information...A new version of Avast database is installed..click for more information" Is this a legitimate notice? Because my Avast blue ball (a) is recently always still and it never turns around .
As if the program is disabled (of course there is no other indication of it being disabled).
-Regarding Firewall, I have the Windows' Firewall always on. Is that not enough? If not, please recommend me one.
- Another very important point that you, as experts, can give me a clue about:
As you know for each hotmail e-mail address, one receives also an MSN explorer browser:
-It seems that the attacker can connect to my PC and attack it, ONLY through 2 of my MSN Browsers. When I am on other MSN Browsers, the constant periodically sucking of data stops. I hope this could give you a clue, how these attacks in my particular case work and where should I look in my PC, to find the problem.
Thank you very much for your help.