If you're getting java errors with the IRC webclient, you may need to add the site to the exceptions list for Java. A recent Java update added some security measures that may, unfortunately, block the web client from working. The error I'm talking about will look something like this:

My first recommendation if you encounter this would be to
connect with a dedicated IRC client. But if you don't want to or cannot do this, the backup option to get around this is to add irc.furtopia.org/chat.php to the java exceptions list. The following is a step-by-step guide to doing this (shown in Window's 7).
In the start menu, go to All Programs, and find Java:

Expand the Java folder, and click 'Configure Java':

This will bring up the Java Control Panel. From here, click the 'Security' tab:

Once in the Security tab, click 'Edit Site List' under the Exception Site List:

This will bring up the Exception Site List dialogue. Click 'Add':

1. In the top box, you can now enter the desired URL to add as an exception. Type in '
http://irc.furtopia.org/chat.php'
2. Click 'Add' after entering the URL:

You will probably get a pop-up warning like what is pictured below. Click 'continue' to allow the site to still be added to the list.

After the pop-up warning goes away, the Exception Site list will remain, with the site successfully added. Click 'OK':

This will return you to the Java Control Panel. Click 'OK':

And you're done! Load up the IRC web client, and it should come up fine without giving that error.