Otra cosa que podrías probar:
Código PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>test</title>
</head>
<body>
<img name="im" id="im" src="newsletter/images/ajax-loader2.gif" width="66" height="66" onerror="this.src='newsletter/images/ajax-loader2.gif?'+Math.random()" onload="_this=this;setTimeout(function(){_this.src=null;},2000)" />
<div id="log"></div>
</body>
</html>