The channel, network and the java IRC client applet should be working at all times.

Sounds like it's a problem with the java app.
Please ensure that you have java installed properly (the link for installing manually can be found on the top in the edit) and that you accept loading the applet by choosing 'yes' when asked. Keep in mind that some school or corporate networks are tight on security and won't allow the use of such java applets to be used, or even loaded.
It may take a little time for the applet to load and launch, of course, so don't be too hasty in branding it malfunctioning.
Otherwise, you may, of course, use a normal IRC client, such as
mIRC, to connect to the chat.
The IRC server the channel is at is irc.chatspike.net. Once you've connected, you may join the Tes F'Ruum chat by typing /join #tes_fruum
Any luck or anything more to add?