How can I remove HTML comment string?

Hi everyone,
I have a problem with the string of comments.
In my other blog (www.artherapy.altervista.org), trying to leave a comment, in the bottom appear a string like this (show the screenshot, please): http://img35.imageshack.us/img35/5994/3fm2.png

I don’t like it and I’d like to remove that.

How can I do?
Can someone help me, please?

Thank you!

Paola

http://wordpress.org/plugins/comments/