Answer
Buzzen help information for this topic.
Buzzen now uses a WebSocket based web chat. If you experience an issue with the chat pane, not loading trying clearing your browser cache as shown in the following faq
/faq/49
Also, some browser addons can stop the WebSocket from loading so check if you have any extensions loaded and if you do disable them one by one and try and see if it chat loads.
Some antiviruses can stop the WebSocket from loading. If this is the case check with the developers of your chosen Antivirus software on how to allow the WebSocket through.