pueba asi
Código PHP:
"SELECT tn.*, tc.*, user_id, user_name FROM ".$db_prefix."news tn
LEFT JOIN ".$db_prefix."users tu ON tn.news_name=tu.user_id
LEFT JOIN ".$db_prefix."news_cats tc ON tn.news_cat=tc.news_cat_id
WHERE ".groupaccess('news_visibility')." AND (news_start='0'||news_start<=".time().") AND (news_end='0'||news_end>=".time().")
ORDER BY news_sticky ASC, news_datestamp ASC LIMIT $rowstart,$items_per_page"
);