Database Issue

Everything is working fine except for the fact that I receive this error when I save or publish a post:

WordPress database error: [Unknown column ‘pc.post_id’ in ‘on clause’]
SELECT cat_ID AS ID, MAX(post_modified) AS last_mod FROM wp_posts p LEFT JOIN wp_post2cat pc ON p.ID = pc.post_id LEFT JOIN wp_categories c ON pc.category_id = c.cat_ID WHERE post_status = ‘publish’ GROUP BY cat_ID

WordPress database error: [Unknown column ‘pc.post_id’ in ‘on clause’]
SELECT cat_ID AS ID, MAX(post_modified) AS last_mod FROM wp_posts p LEFT JOIN wp_post2cat pc ON p.ID = pc.post_id LEFT JOIN wp_categories c ON pc.category_id = c.cat_ID WHERE post_status = ‘publish’ GROUP BY cat_ID

Thanks in advance for your help.

-Dave