I was trying to post an answer, but then it asked for Captcha to check whether I am human. The Captcha loader is shown, but the Captcha is not loaded and I couldn't post the answer.

When I checked the ajax call using the Developer Toolkit, it showed the request http://api.recaptcha.net/js/recaptcha_ajax.js?_=1383826516487 returned a 404 error.

Please check the recaptcha is working before showing the captcha.