Help needed with “WordPress database error”

I have a newish WP blog. When posting today I got the following error message –

“WordPress database error: [Table ‘web91-recipe-wp.wp_post2cat’ doesn’t exist] 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”

As a WP novice I have no idea what might have caused this or where to start looking to rectify the problem.

Any help, advice or guidance will be much appreciated.

Regards

Mentorman