MyBB SQL Error

MyBB has experienced an internal SQL error and cannot continue.

SQL Error:
126 - Incorrect key file for table './gimpforu_db/mybb_sessions.MYI'; try to repair it
Query:
REPLACE INTO mybb_sessions SET `uid`='0',`sid`='aaad7d0ac0ccc824a5a0ff2b4f64d1ae',`time`='1418863238',`ip`='54.87.89.176',`location`='/forumdisplay.php?google_seo_forum=plugins',`useragent`='CCBot/2.0 (http://commoncrawl.org/faq/)',`location1`='0',`location2`='0',`nopermission`='0'