Categories Missing and taxonomy.php

I installed WordPress for a client on their hosting service, and was getting a blank page instead of it completing the installation process.
(the same as this post: http://wordpress.org/support/topic/157336?replies=3)

I was told by the host support team, that there was a problem with PHP 5 on NS12, and that I had to edit the taxonomy.php file (in wp-includes) to remove (object) from the following lines in the file:

$wp_taxonomies = array();
$wp_taxonomies[‘category’] = (object) array(‘name’ => ‘category’, ‘object_type’ => ‘post’, ‘hierarchical’ => true, ‘update_count_callback’ => ‘_update_post_term_count’);
$wp_taxonomies[‘post_tag’] = (object) array(‘name’ => ‘post_tag’, ‘object_type’ => ‘post’, ‘hierarchical’ => false, ‘update_count_callback’ => ‘_update_post_term_count’);
$wp_taxonomies[‘link_category’] = (object) array(‘name’ => ‘link_category’, ‘object_type’ => ‘link’, ‘hierarchical’ => false);

Bingo! Everything was good and working. However, since then, I’ve found that when adding categories, they don’t show up in the template sidebar – only the uncategorized category, (even when there are posts associated with them), and in the categories admin panel, the count for each category shows as 0 (other than the uncategorized category which shows 1, even though I’ve deleted the installation post).

On page, where the categories show at the top of each post, I can navigate to the correct category.

I have a feeling this is related to removing the (object) from taxonomy.php, but don’t know how to proceed from here.

Does anyone have any insights?