I have the same problem irrespective of whether an URL has been supplied or not.

In case where an URL has not been supplied by the Commentator, the "http://" appears in the Input as NealO has briefed above.

The "http://" gets saved into the comments table.

To fix this, find

$this->author_url = (!stristr($url, '://')) ? 'http://'.$url : $url;

in blogs/inc/MODEL/comments/_comment.class.php and replace it with

if( ! empty($url) && ! preg_match( '~^\w+://~', $url ) )
{ // URL given and does not start with a protocol:
  $url = 'http://'.$url;
}

This allows commenters to use the A tag (see /conf/_formatting.php IIRC):

$comments_allowed_tags['a'] = C_E_a_content;

Thanks blue...

I didn't get the last bit though.

This allows commenters to use the A tag (see /conf/_formatting.php IIRC):

Should it be added to the

$comments_allowed_tags = array

or

$comments_allowed_tags += array

Cheers

Just add the line like it is at the end. Or search the line that looks similar and uncomment it (IIRC).