Chat plugin stopped working

I've had the Chat plugin running fine, until the most recent update which seems to have stopped it in it's tracks for me. Please see the attachment:

http://www.eastangliasubbuteo.co.uk/?attachment_id=3284

As you can see the message box has shrunk, and upon pressing 'enter' it simply moves down a line rather than sends the message to the live chat. Please advise, thank you.