You have not registered
When I connect to a server, I get this message:
You have not registered PING You have not registered 451 PING You have not registered
And other variations on the theme.
This message is not related to any NickServ registration, but is a server-level message saying that your IRC session is not yet established with the server.
The reason is that when you tried to connect, the server told you to chose a different nick name, and you either closed the dialog without selecting another nick, or the dialog timed out waiting for your answer.
There can only be one instance of any given nick name on a particular IRC network at a time, perhaps the one you chose is taken, or otherwise in use?