I noticed it because it was connecting on irc.quakenet.com continuously! It was a file named schot.exe in the system32 folder. I tried to scan the file with nod32 (v2 latest update) and it didn't detect it at all. Finally I used an online virus scanner that succeed to identify the virus. It's an old virus in nod32 database since 2002. Finally I have dowloaded and installed the nod32 beta and... miracle it works! the beta detected the virus. Could you explain me why nod32 v2 can not always detect virus that are well known?