Hozzáférés megtagadva

Néhány napja a weblapom a következő hibaüzenetet írja ki:

user warning: Can't create/write to file '/var/lib/mysql/.tmp/#sql_df7_0.MYI' (Errcode: 30) query: SELECT DISTINCT(p.perm) FROM role r INNER JOIN permission p ON p.rid = r.rid WHERE r.rid IN (1) in /var/www/html/includes/database.mysql.inc on line 172.
user warning: Incorrect key file for table './drupal/watchdog.MYI'; try to repair it query: INSERT INTO watchdog (uid, type, message, severity, link, location, referer, hostname, timestamp) VALUES (0, 'access denied', 'node/1', 1, '', 'http:///', 'http:///?q=node/23', '', 1344425621) in /var/www/html/includes/database.mysql.inc on line 172.
user warning: Can't create/write to file '/var/lib/mysql/.tmp/#sql_df7_0.MYI' (Errcode: 30) query: SELECT DISTINCT b.* FROM blocks b LEFT JOIN blocks_roles r ON b.module = r.module AND b.delta = r.delta WHERE b.theme = 'twilight' AND b.status = 1 AND (r.rid IN (1) OR r.rid IS NULL) ORDER BY b.region, b.weight, b.module in /var/www/html/includes/database.mysql.inc on line 172.

Kérem, aki tud segítsen nekem, hogy hol keressem a hibát.