Suddenly this error shows up the I try to access the module manager. Any help is greatly appreciated!

500 - An error has occurred.

Got error 28 from storage engine SQL=SELECT a.id, a.title, a.note, a.position, a.module, a.language,a.checked_out, a.checked_out_time, a.published+2*(e.enabled-1) as published, a.access, a.ordering, a.publish_up, a.publish_down,l.title AS language_title,uc.name AS editor,ag.title AS access_level,MIN(mm.menuid) AS pages,e.name AS name FROM `jos_modules` AS a LEFT JOIN `jos_languages` AS l ON l.lang_code = a.language LEFT JOIN jos_users AS uc ON uc.id=a.checked_out LEFT JOIN jos_viewlevels AS ag ON ag.id = a.access LEFT JOIN jos_modules_menu AS mm ON mm.moduleid = a.id LEFT JOIN jos_extensions AS e ON e.element = a.module WHERE (a.published IN (0, 1)) AND a.client_id = 0 AND e.client_id =0 GROUP BY a.id, a.title, a.note, a.position, a.module, a.language,a.checked_out,a.checked_out_time, a.published, a.access, a.ordering,l.title, uc.name, ag.title, e.name,l.lang_code, uc.id, ag.id, mm.moduleid, e.element, a.publish_up, a.publish_down,e.enabled Got error 28 from storage engine SQL=SELECT a.id, a.title, a.note, a.position, a.module, a.language,a.checked_out, a.checked_out_time, a.published+2*(e.enabled-1) as published, a.access, a.ordering, a.publish_up, a.publish_down,l.title AS language_title,uc.name AS editor,ag.title AS access_level,MIN(mm.menuid) AS pages,e.name AS name FROM `jos_modules` AS a LEFT JOIN `jos_languages` AS l ON l.lang_code = a.language LEFT JOIN jos_users AS uc ON uc.id=a.checked_out LEFT JOIN jos_viewlevels AS ag ON ag.id = a.access LEFT JOIN jos_modules_menu AS mm ON mm.moduleid = a.id LEFT JOIN jos_extensions AS e ON e.element = a.module WHERE (a.published IN (0, 1)) AND a.client_id = 0 AND e.client_id =0 GROUP BY a.id, a.title, a.note, a.position, a.module, a.language,a.checked_out,a.checked_out_time, a.published, a.access, a.ordering,l.title, uc.name, ag.title, e.name,l.lang_code, uc.id, ag.id, mm.moduleid, e.element, a.publish_up, a.publish_down,e.enabled ORDER BY `position` asc,a.ordering ASC LIMIT 0, 20 Got error 28 from storage engine SQL=SELECT a.id, a.title, a.note, a.position, a.module, a.language,a.checked_out, a.checked_out_time, a.published+2*(e.enabled-1) as published, a.access, a.ordering, a.publish_up, a.publish_down,l.title AS language_title,uc.name AS editor,ag.title AS access_level,MIN(mm.menuid) AS pages,e.name AS name FROM `jos_modules` AS a LEFT JOIN `jos_languages` AS l ON l.lang_code = a.language LEFT JOIN jos_users AS uc ON uc.id=a.checked_out LEFT JOIN jos_viewlevels AS ag ON ag.id = a.access LEFT JOIN jos_modules_menu AS mm ON mm.moduleid = a.id LEFT JOIN jos_extensions AS e ON e.element = a.module WHERE (a.published IN (0, 1)) AND a.client_id = 0 AND e.client_id =0 GROUP BY a.id, a.title, a.note, a.position, a.module, a.language,a.checked_out,a.checked_out_time, a.published, a.access, a.ordering,l.title, uc.name, ag.title, e.name,l.lang_code, uc.id, ag.id, mm.moduleid, e.element, a.publish_up, a.publish_down,e.enabled ORDER BY `position` asc,a.ordering ASC