When Role Scoper is turned on, and I make a call to get_categories("child_of=1″) while accessing the site anonymously (not logged in), it generates the following database error:

WordPress database error: [Unknown column 'wp_posts.post_type' in 'where clause']
      SELECT DISTINCT t.*, tt.* FROM wp_terms AS t INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id WHERE 1=1 AND ( ( ( ( wp_posts.post_type = 'post' ) ) ) ) AND tt.taxonomy IN ('category') ORDER BY t.name ASC

If I access the site as any logged-in user (or disable Role Scoper), the error goes away and it functions as expected.