WP Comment meta corrupt – how do I fix?

I am getting the following error – what am I meant to do to fix it?

1272909837WordPress database error Table ‘./databaseusername_websitename/wp_commentmeta’ is marked as crashed and should be repaired for query INSERT INTO wp_commentmeta (comment_id,meta_key,meta_value) VALUES (‘1690′,’_wp_trash_meta_status’,’0′) made by wp_spam_comment, add_comment_meta, add_metadata