If you copied code from the aberdeen_breadcrumb function into a custom sub-theme's template.php file you should compare your code to the changes to ensure that menu_get_active_title() is properly wrapped in check plain like:
- Initial commit of Drupal 6 version #178323: Drupal 6
- Moved some images into folder for better file management
- Liquid and Fixed layouts tested in Firefox, IE, Safari, Chrome, and Opera