My computer froze up while I was on Chat tonight and I got knocked off.  Now I can't reconnect.  I get the message: 
Connecting...
Unable to connect : null
I tried to connect direct from shadowfire with the same result.
Any suggestions?
<b>Further Update</b>
I was able to get back on this morning so the problem seems to have solved itself.  For others with the same problem, here's a link to the irc help page. 
http://www.pjirc.com/help.php
It offers a number of solutions, but I guess time was all I needed.