There hasn't been any downtime lately. You might try connecting on a different port (available ports are: 1080, 5000, 5555, 6660-6670, 8080). If that doesn't work, you can also provide the message you're receiving here so we can try to help you further.
Are you sure that you are using the proper irc server? IRC Server: irc.swc-irc.com
Edit: I had a problem that was identical to this, when I had to download irc again.(it somehow was deleted when I let somebody use my com) As soon as I set the server correctly, all was fine.
Time for a new computer Tal.:P I have been having issues staying connected lately, but so far no issues logging on. There have been a couple of situations where I was disconnected and had to completely exit and restart, to reconnect. I have no idea if what I'm experiencing is connected with any other problem, but I guess it's possible.
That's probable; many schools block IRC ports. 8080 is the most likely to work.
Otherwise, the school may be blocking the software, in case you might want to look into a CGI program like mibbit to connect (although mibbit may not always work because the number of permitted mibbit connections to the server is limited).