You're using $PHP_SELF variable in your script in a 404 Webpage Error. The $PHP_SELF is use to output the
background="/img/f/mexRed">
and
<div id="imgmexRed"
html code. I'm a bit surprise that I couldn't download your image using a offline browser but the use of $PHP_SELF in the script reduce ALOT of utilites of your script. The image protect will be only use in one html webpage.