After completing the registration page I got this error.
I did receive the registration email and was able to log in. I did not receive any “further instructions” email. So either the captcha isn’t working or it’s throwing a false alarm.
Before registering I did try to log in twice — I wasn’t sure if I had an account here so I tried two email addresses — but that was before I ever went to the registration page.
Bonus bug: when I tried to Preview this post I got an error page.
FIrefox 25.0.1 on OS X 10.9
– John