in the js/lighter/Fuel.php.js file, change line 64 - 65;
start: this.strictRegExp('<?php', '<?=', '<%', '<script language="php">'),
end: this.strictRegExp('?>', '%>', '</script>')
to:
start: this.strictRegExp('<'+'?php', '<'+'?=', '<'+'%', '<scr'+'ipt language="php">'),
end: this.strictRegExp('?'+'>', '%'+'>', '</scr'+'ipt>')
Your server is configured to process any page with .php in the name as a php page, most servers will only process pages that end in .php as php code