Thanks for your answer

Well:

CHECK YOUR FIREWALL => done
DISCONNECT/RECONNECT LW => I don't find it
UPDATE/REINSTALL JAVA => there is no Mac update
CHANGE LISTEN ON PORT => done
PURGE DOWNLOAD QUEUE => there is no queue
DELETE LIMEWIRE'S PREFERENCES FOLDER => done
DELETE gnutella.net FILE (LW 5.0 users only) => done
DISABLE ULTRAPEER CAPABILITIES, DHT & TLS => I don't understand...