MyBB SQL Error

MyBB has experienced an internal SQL error and cannot continue.

SQL Error:
144 - Table './sql15202/mybb_posts' is marked as crashed and last (automatic?) repair failed
Query:
SELECT u.*, u.username AS userusername, p.* FROM mybb_posts p LEFT JOIN mybb_users u ON (u.uid=p.uid) WHERE p.tid='287370' AND p.visible='1' ORDER BY p.dateline LIMIT 0, 10