plugin causing error

Hi there,
Just tried using your plugin. Installation worked without issue but I was just testing it to make a comment on my website post and it shows the following error when making a comment and putting in the correct Captcha code:

“Error 1: Click back and type in the password.”

is there anything i can do to solve this error? I have given all the relevant permissions on the plugins directory and i have tried with and without PHP…

http://wordpress.org/extend/plugins/si-captcha-for-wordpress/