Blog in question: http://www.starwalkerblog.com
On the comments form, the 'submit' button doesn't work. It sends the user back to the homepage of the blog and the comment is not submitted.
I have checked through comments.php, and everything looks in order. I have replaced the comments.php file with one that works on another site, and that didn't work. I have checked and replaced the wp-comments-post.php file with one I know works, and that didn't work either.
I don't know what else to check. I have a test site with the same theme at http://www.apocalyspeblog.com/starwalker - comments work fine on that one!