SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.3.6): Invalid SQL: DELETE FROM bb1_sessions WHERE userid='0' AND ipaddress = '54.198.142.255' AND useragent = 'CCBot/2.0 (http://commoncrawl.org/faq/)'
mysql error: Table './db00018629/bb1_sessions' is marked as crashed and should be repaired
mysql error number: 145
mysql version: 5.0.95
php version: 5.2.17
Date: 21.08.2014 @ 08:17
Script: /thread27800.html
Referer: