are you talking about the W32/Virut, it's been out there for about a year. It has been identified as being triggered by one of these:
%System%\aewuuwufbvv.exe
%System%\arowzdrkjgtwr.exe
%System%\bgzmdaaauies.exe
%System%\bkzzrtliuprckz.exe
%System%\dllcache\sxch0st.exe
%System%\dllcache\wintcps.exe
%System%\ewmtgqkh.exe
%System%\explorer.exe
%System%\gyvtncthhidoir.exe
%System%\ifbtomotphe.exe
%System%\ikpprhznityacq.exe
%System%\irmwsyf.exe
%System%\khjdphmyttggvt.exe
%System%\lhttk.exe
%System%\mwaehuczvshuh.exe
%System%\mzdgz.exe
%System%\naszaoytn.exe
%System%\ocekhdcr.exe
%System%\orqbhjddhbfp.exe
%System%\qwkoykyojjn.exe
%System%\ruqbcalrxsfw.exe
%System%\sgvq.exe
%System%\sgwnlbki.exe
%System%\wbem\winscrvs.exe
%System%\xirwqznybc.exe
%System%\xroyiabh.exe
%System%\yvscb.exe
%System%\zeuvqlghbbfv.exe
%System%\zoxtyjayxnkwuh.exe
%ProgramFiles%\common files\system\msasp32.exe
%ProgramFiles%\common files\system\msiwa32.exe
%Windir%\antiv.exe
All the top anti-virus software find and remove it before it has a chance to trigger. As skuzzy stated the initial infection is generally in sleeper mode and no telling what might casuse it to popup. Once it does trigger your operating system is pretty much fryed. found this on the internet
http://www.softpedia.com/get/Antivirus/Win32-Virut-Remover.shtml good luck