Question DB function failed et 500 - Une erreur s'est produite

bonjour à tous,

j'utilise joomla 15.22 et virtuemart 118.
Ce matin j'étais tranquillement en train de gérer mon site (en Joomla) quand tout à coup, plus d'accès aux modules ni aux articles. Voici ce qui s'affiche:

Gestion des modules:

DB function failed with error number 1030
Got error 28 from storage engine SQL=SELECT m.*, u.name AS editor, g.name AS groupname, MIN(mm.menuid) AS pages FROM jos_modules AS m LEFT JOIN jos_users AS u ON u.id = m.checked_out LEFT JOIN jos_groups AS g ON g.id = m.access LEFT JOIN jos_modules_menu AS mm ON mm.moduleid = m.id WHERE m.client_id = 0 GROUP BY m.id ORDER BY m.position , m.ordering ASC LIMIT 0, 20

gestion des articles:

500 - Une erreur s'est produite
DB function failed with error number 1030
Got error 28 from storage engine SQL=SELECT c.*, g.name AS groupname, cc.title AS name, u.name AS editor, f.content_id AS frontpage, s.title AS section_name, v.name AS author FROM jos_content AS c LEFT JOIN jos_categories AS cc ON cc.id = c.catid LEFT JOIN jos_sections AS s ON s.id = c.sectionid LEFT JOIN jos_groups AS g ON g.id = c.access LEFT JOIN jos_users AS u ON u.id = c.checked_out LEFT JOIN jos_users AS v ON v.id = c.created_by LEFT JOIN jos_content_frontpage AS f ON f.content_id = c.id WHERE c.state != -2 ORDER BY section_name , section_name, cc.title, c.ordering LIMIT 0, 20

ouf! je ne sais par quel miracle tout ceci revient dans l'ordre!!
En parallèle mon menu de la boutique (swMenuFree) disparait lui aussi du site. et réapparait!

quelqu'un peut-il me dire ce qui se passe?

Merci pour vos infos très précieuses.

nathalie