This has been happening to me not only with phpbb but with xenforo as well. It has happened twice in total throughout my 16 months of hosting. Once with phpbb and just now once with xenforo about a few days after my switch (from phpbb to xenforo) Basically; entire site goes offline and the only way for me to fix it is to restart the vps, hop in phpmyadmin and run a table repair. After restarting the vps the site comes back up but nothing works whatsoever and this error is shown. Server Error Mysqli statement execute error : Incorrect key file for table './andymidu_xen/xf_session.MYI'; try to repair it Zend_Db_Statement_Mysqli->_execute() in Zend/Db/Statement.php at line 297 Zend_Db_Statement->execute() in Zend/Db/Adapter/Abstract.php at line 479 Zend_Db_Adapter_Abstract->query() in Zend/Db/Adapter/Abstract.php at line 574 Zend_Db_Adapter_Abstract->insert() in XenForo/Session.php at line 690 XenForo_Session->saveSessionToSource() in XenForo/Session.php at line 431 XenForo_Session->save() in XenForo/Controller.php at line 403 XenForo_Controller->updateSession() in XenForo/Controller.php at line 350 XenForo_Controller->postDispatch() in XenForo/FrontController.php at line 317 XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 132 XenForo_FrontController->run() in /home/andymidu/public_html/forum/index.php at line 13 PHPmyadmin also shows this after table repair: .xf_session repair warning Number of rows changed from 871 to 1186 After running the table repair the site is once again fully functional and all is perfectly well. Any ideas "why" this happens however?