THese are nothing but spam postings, there are spammers who keep doing it occasionally. All we can do is try to block them but they keep popping under new user names for a few days and then disappear. We have seen this before too. All I can do is try and keep blocking them but there is no way we can deter them from joining under new user names.
"I am free of all prejudice. I hate everyone equally." - W. C. Fields :)
