Thanks, I suspected this might have been the issue, thanks
Surya Aditya Paturi commented
It seems you have mistakenly entered the comment text in the text box provided for entering the guest's name while logging in as guest. For commenting as a guest you need to first sign in as a guest by entering your name and solving the captcha after click on "Comment as Guest". Only then you will be able to comment.
Please let us know in detail if this is not the issue you are referring to.