PHP text-size selector within a Drupal site only working when logged in

[voodoo_tr]

I have a PHP text-size select function within a Drupal site:It uses this selector...:\[code\]<ul id="font-sizes"> <li class="one"><a href="http://stackoverflow.com/questions/2100945/<?php global $base_url; print $base_url;?>/sites/all/themes/x/resize.php?set=small">Normal Font-Size</a></li> <li class="two"><a href="http://stackoverflow.com/questions/2100945/<?php global $base_url; print $base_url;?>/sites/all/themes/x/resize.php?set=medium">Medium Font-Size</a></li> <li class="three"><a href="http://stackoverflow.com/questions/2100945/<?php global $base_url; print $base_url;?>/sites/all/themes/x/resize.php?set=large">Large Font-Size</a></li></ul>\[/code\]...which modifies a stylesheet link...:\[code\]<link rel="stylesheet" type="text/css" media="screen" href="http://stackoverflow.com/questions/2100945/<?php global $base_url; print $base_url;?>/sites/all/themes/x/<?php echo isset($_COOKIE['sitestyle'])?$_COOKIE['sitestyle']:'small'; ?>.css" />\[/code\]... by using this file (resize.php):\[code\]<?php setcookie ('sitestyle', $_GET['set'], time()+31536000,'/', 'mysite.co.uk', '0'); header("Location: ".$_SERVER['HTTP_REFERER']); ?>\[/code\]Now, my problem is that it works fine when logged into the CMS (as the main admin or a lower level role), but it just does not work when accessing the site as an anonymous user. I've been through the permissions settings, but I can't for the life of me see anything that would affect this. I'm guessing therefore it's do to with some higher-level PHP access thing that is beyond me.Any ideas?