Well no answer to my post about your modem...
So as one last ditch effort, because you have tried absolutley eveything we can think of, try installing PeerGuardian, it will help keep the fake hosts out...Remember to enable PG just before you start limewire up...
Phoenix Labs » PeerGuardian 2 If that doesn't work, you will need to go and buy a new modem/router and make sure it's an easy one to Port Forward...