This is a question that has been dealt with a lot on the message boards. Please learn to use the
Search feature and to read the bookmarked posts first.
On that note, there's
this post by Merlin that explains common IRC connection errors (among them the one that you're describing) and there's
this thread that might help you find a server if you're encountering the error on DALnet.
Finally, there's an
edition of the DALnet zine that explains the problems that the network has been having.
