[SOLVED] Template 15: Error in Firefox

Hello. I thank the beautiful site that has free templates.

In Firefox I get this error, despite not having removed the reference to this site:

"You have removed or modified the link to our website. In accordance with our terms of use you must keep intact and visible any notice accompanying this product !"

Site: http://www.avatarmugs.com/avatar/

Safari does not appear in the pop and do not understand why it appears in Firefox. I was modifying the template on my computer and did not show the message, but when I put it to the network started to appear for no reason.
Is this problem a bug?

And the newsletter don´t work. The newsletter.php only contain this code:
<?
// ----- Traitement newsletter ----- //


// --------------------------------- //

header("Location: ./index.htm?page=_newsletter_message.htm");
?>


Thanks.