Try changing line 152 in your comments-template.php file from:
if ( empty( $url ) || 'http://' == $url )
to if ( empty( $url ) || 'http://' == $url || 'Website' == $url)
Try changing line 152 in your comments-template.php file from:
if ( empty( $url ) || 'http://' == $url )
to if ( empty( $url ) || 'http://' == $url || 'Website' == $url)