I assume that the problem is caused by Google Analytics, namely the “track outgoing clicks” feature (as recalled, might be inaccurate feature name). “Track outgoing links” adds some JavaScript code to all outgoing links, and that script has tick characters like this one ‘ which, incidentally, are also used for delimiting the values of comment anchor tags.

To fix:

1. locate file wp-includes/comment-template.php
2. in that file, find the get_comment_author_link function (lines 140-150 in WP 2.7.1)
3. replace the line
   1. $return = "<a href='$url' rel='external nofollow' class='url'>$author</a>";

   with

   1. $return = '<a href="'.$url.'" rel="external nofollow" class="url">'.$author.'</a>';

This helped me and might help you.

It adds Referrer of the person who’s leaving comment on your WP blog. May help to take the right action for seemingly legit, but really spam comments (e.g. if someone was just searching for blogs with enabled commenting to leave a comment with name linked to their biz-website).