Recently I switched to Google Chrome. Up until last night I'd had no problems with it in our forums, but then suddenly all the text entry boxes (like the message reply box, for example, were filled with Non-Unicode blank squares.

I thought at first that a Chrome update might have screwed something up, but on closing Chrome and then restarting it the problem disappeared.

So if you're using Chrome and you experience that same problem, just close the browser and restart it, and hopefully that will sort things.