Thanks for the answer, I thought all already gone to the beach !
Perhaps my explanation was not clear.
Infected file has not arrived to me through e-mail but through the file transfer with the MSN Messenger.
1) After the first notice of presence of the virus the avast has opened the usual window with possible actions, but pressing on any key (Delete, Move/Rename,Repair....) error message appeared me:"
Cannot process"C:/Documenti/File ricevuti/......2002.exe" file .
2) For progress I have had to press the key OK.
3) L'avast warn again me of presence of virus.
4) This time if I press the key "Delete" virus is eliminated.
My question: because the first time the file was not accessible (cannot process).
I hope that this time is clearer.
Thanks