SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.3.6): Invalid SQL: DELETE FROM bb1_sessions WHERE userid='0' AND ipaddress = '23.20.44.136' AND useragent = 'CCBot/2.0 (http://commoncrawl.org/faq/)'
mysql error: Table './dbadsbe/bb1_sessions' is marked as crashed and should be repaired
mysql error number: 145
mysql version: 5.1.73
php version: 5.3.3
Date: 28.07.2014 @ 18:23
Script: /wbb2/thread.php?threadid=6619
Referer: