The IRC works just fine (using a IRC client). For this to work in your web browser you will need to have flash enabled. With all the security flaws flying around with adobe flash we are starting to see browsers disable it by default. If you would like this to work you'll need to look for a work around/enable flash somehow.
I highly suggest you completely move over to push notifications for all aspects as it is MUCH faster and works across all platforms without the requirement of flash. (only down side is no sounds but you do get a popup).