Here are the contents of the log file....

[16-Jul-2015 10:12:43 Europe/Paris] PHP Warning: require_once(includes/classes/categories_ul_generator.php): failed to open stream: No such file or directory in C:\wamp\www\zencart\includes\templates\template333\common\tpl_drop_menu.php on line 59

[16-Jul-2015 10:12:43 Europe/Paris] PHP Stack trace:

[16-Jul-2015 10:12:43 Europe/Paris] PHP 1. {main}() C:\wamp\www\zencart\index.php:0

[16-Jul-2015 10:12:43 Europe/Paris] PHP 2. require() C:\wamp\www\zencart\index.php:97

[16-Jul-2015 10:12:43 Europe/Paris] PHP 3. require() C:\wamp\www\zencart\includes\templates\template_default\common\tpl_main_page.php :73

[16-Jul-2015 10:12:43 Europe/Paris] PHP 4. require() C:\wamp\www\zencart\includes\templates\template333\common\tpl_header.php:131

[16-Jul-2015 10:12:43 Europe/Paris] PHP Fatal error: require_once(): Failed opening required 'includes/classes/categories_ul_generator.php' (include_path='.;C:\php\pear') in C:\wamp\www\zencart\includes\templates\template333\common\tpl_drop_menu.php on line 59

[16-Jul-2015 10:12:43 Europe/Paris] PHP Stack trace:

[16-Jul-2015 10:12:43 Europe/Paris] PHP 1. {main}() C:\wamp\www\zencart\index.php:0

[16-Jul-2015 10:12:43 Europe/Paris] PHP 2. require() C:\wamp\www\zencart\index.php:97

[16-Jul-2015 10:12:43 Europe/Paris] PHP 3. require() C:\wamp\www\zencart\includes\templates\template_default\common\tpl_main_page.php :73

[16-Jul-2015 10:12:43 Europe/Paris] PHP 4. require() C:\wamp\www\zencart\includes\templates\template333\common\tpl_header.php:131