Hi burners - thanks for letting me know about this. I'll have a look in to this when I'm back home (3rd Jan) and investigate in more detail. I've only got a few mins access to the computer, but wanted to let you know I'll check it out.
We're using "Recaptcha" from Google and it worked for me when I tried it a few moments ago, so I wonder if this was just a temporary problem. If you tried 20 times then something has gone wrong somewhere - sorry about that!
Has anyone else had a similar problem?