message error : after delete cach, no error message

In maintenance and in product.
I used Drupal in this config :

Drupal 6.13

GIF Read Support, GIF Create Support, JPG Support, PNG Support, WBMP Support, XPM Support, XBM Support, FreeType Support with freetype
AMFPHP 1.9 Beta 2
Accès au fichier update.php Protégé
Base de données MySQL 5.0.44

Boîte à outils image The imagemagick toolkit is installed.
CAPTCHA Already 152 blocked form submissions
CTools CSS Cache Exists
Etat de mise à jour de Drupal core A jour
Fichier de configuration Protégé
Image module directories Exists (sites/default/files/images).
ImageMagick advanced options ImageMagick image toolkit is selected.
Javascript libraries directory Exists
Librairie GD bundled (2.0.34 compatible)
Librairie Unicode Extension PHP mbstring
Memcache 1.2.6
Memcache admin Memcache included
Mise à jour de la base de données A jour
Notification des mises à jour Activé
PHP 5.2.5-pl1-gentoo
PHP 'register globals' Désactivé
Patches All patches applied
There are 2 patches available and applied.
Plafond mémoire de PHP 512M
Publicbookings resources At least one resource is defined.
SWFObject API Installed correctly
Search Lucene API 1.7.6
The officially supported Zend Framework components are installed.
Serveur web Apache/2.0.59 (Unix) mod_ssl/2.0.59 OpenSSL/0.9.8g
Statut de mise à jour des modules et thèmes A jour
Système de fichiers Inscriptible (méthode de téléchargement privée)
Tâches de maintenance cron Dernière exécution il y a 4 sec
Vous pouvez lancer le cron manuellement.
Upload progress Non activé
Your server is capable of displaying file upload progress, but does not have the required libraries. It is recommended to install the PECL uploadprogress library (preferred) or to install APC.
Zlib library Activé
cURL Activé
jQuery UI 1.5.3
jQuery Update 1.2.6

With "performance" and boost module I deleted cached files, one cron runned and "one night", this morning, this error message no display in status.

Now it's ok.

Driss