Error

Zend_Db_Statement_Mysqli_Exception: Mysqli prepare error: Table './mcforums_admin/xf_session' is marked as crashed and should be repaired - library/Zend/Db/Statement/Mysqli.php:77 Generated By: Unknown Account, A moment ago
Stack Trace
#0 /home/mcforums/public_html/library/Zend/Db/Statement.php(115): Zend_Db_Statement_Mysqli->_prepare('DELETE FROM `xf...') #1 /home/mcforums/public_html/library/Zend/Db/Adapter/Mysqli.php(381): Zend_Db_Statement->__construct(Object(Zend_Db_Adapter_Mysqli), 'DELETE FROM `xf...') #2 /home/mcforums/public_html/library/Zend/Db/Adapter/Abstract.php(478): Zend_Db_Adapter_Mysqli->prepare('DELETE FROM `xf...') #3 /home/mcforums/public_html/library/Zend/Db/Adapter/Abstract.php(661): Zend_Db_Adapter_Abstract->query('DELETE FROM `xf...') #4 /home/mcforums/public_html/library/XenForo/Session.php(827): Zend_Db_Adapter_Abstract->delete('xf_session', 'expiry_date < 1...') #5 /home/mcforums/public_html/library/XenForo/CronEntry/CleanUp.php(23): XenForo_Session->deleteExpiredSessions() #6 [internal function]: XenForo_CronEntry_CleanUp::runHourlyCleanUp(Array) #7 /home/mcforums/public_html/library/XenForo/Model/Cron.php(357): call_user_func(Array, Array) #8 /home/mcforums/public_html/library/XenForo/Deferred/Cron.php(24): XenForo_Model_Cron->runEntry(Array) #9 /home/mcforums/public_html/library/XenForo/Model/Deferred.php(294): XenForo_Deferred_Cron->execute(Array, Array, 7.99999809265, '') #10 /home/mcforums/public_html/library/XenForo/Model/Deferred.php(428): XenForo_Model_Deferred->runDeferred(Array, 7.99999809265, '', false) #11 /home/mcforums/public_html/library/XenForo/Model/Deferred.php(373): XenForo_Model_Deferred->_runInternal(Array, NULL, '', false) #12 /home/mcforums/public_html/deferred.php(23): XenForo_Model_Deferred->run(false) #13 {main}
Request State
array(3) { ["url"] => string(33) "http://mc-forums.org/deferred.php" ["_GET"] => array(0) { } ["_POST"] => array(4) { ["_xfRequestUri"] => string(10) "/admin.php" ["_xfNoRedirect"] => string(1) "1" ["_xfToken"] => string(8) "********" ["_xfResponseType"] => string(4) "json" } }