[Admin]

In forumdisplay.php, find these bits of code:

      $thread[rating]='clear.gif';
      eval("\$threadrating = \"".gettemplate('forumdisplaybit_threadrate')."\";");

      $thread[rating]='clear.gif';
      $thread[votenum] = '0';

				if ($thread[votenum] >= $showvotes) {
					$rating = intval(round($thread[voteavg]));
					$thread[rating] = $rating . 'stars.gif';
				} else {
					$thread[rating] = 'clear.gif';
				}

And chage clear.gif to unrated.gif in every one of them.