Problemi con esecuzione cron

Non riuscivo più ad eseguire il cron e, aprendo le pagine di amministrazione mi visualizza una serie di errori:

"Warning: MySQL server has gone away query: INSERT INTO watchdog (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (1, 'php', '%message in %file on line %line.', 'a:4:{s:6:\"%error\";s:12:\"user warning\";s:8:\"%message\";s:849909:\"MySQL server has gone away\nquery: UPDATE cache_update SET data = 'a:45:{s:13:\\"advanced_help\\";a:10:{s:5:\\"title\\";s:13:\\"Advanced help\\";s:10:\\"short_name\\";s:13:\\"advanced_help\\";s:10:\\"dc:creator\\";s:9:\\"dmitrig01\\";s:11:\\"api_version\\";s:3:\\"6.x\\";s:17:\\"recommended_major\\";s:1:\\"1\\";s:16:\\"supported_majors\\";s:1:\\"1\\";s:13:\\"default_major\\";s:1:\\"1\\";s:14:\\&quot in /includes/database.mysqli.inc on line 135..................."

e nel riquadro sotto (es. Amministra):

"user warning: MySQL server has gone away query: UPDATE cache_update SET data = 'a:45:{s:13:\"advanced_help\";a:10:{s:5:\"title\";s:13:\"Advanced help\";s:10:\"short_name\";s:13:\"advanced_help\";s:10:\"dc:creator\";s:9:\"dmitrig01\";s:11:\"api_version\";s:3:\"6.x\";s:17:\"recommended_major\";s:1:\"1\";s:16:\"supported_majors\";s:1:\"1\";s:13:\"default_major\";s:1:\"1\";s:14:\"project_status\";s:9:\"published\";s:4:\"link\";s:39:\"http://drupal.org/project/advanced_help\";s:8:\"releases\";a:7:{s:7:\"6.x-1.2\";a:20:{s:4:\"name\";s:21:\"advanced_help 6.x-1.2\";s:7:\"version\";s:7:\"6.x-1.2\";s:3:\"tag\";s:13:\"DRUPAL-6--1-2\";s:13:\"version_major\";s:1:\"1\";s:13:\"version_patch\";s:1:\"2\";s:6:\"status\";s:9:\"published\";s:12:\"release_link\";s:29:\"http://drupal.org/node/424468\";s:13:\"download_link\";s:65:\"http://ftp.drupal.org/files/projects/advanced_help-6.x-1.2.tar.gz\";s:4:\"date\";s:10:\"1238954409\";s:6:\"mdhash\";s:32:\"a41a31032c907409ab5c330260c66fe8\";s:8:\"filesize\";s:5:\"79326\";s:5:\"files\";s:4:\"\n \";s:4:\"file\";s:10:\"\n \n \";s:3:\"url\";s:127:\"http://ftp.drupal.org/files/projects/advanced_help-6.x-1.2.tar.gzhttp://...\";s:12:\"archive_type\";s:9:\"tar.gzzip\";s:3:\"md5\";s:64:............"

mi è stato consigliato di caricare un file nominandolo temp.php:

"

<?php
require_once './includes/bootstrap.inc';
drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
db_query("update system set status='0' where name='update'");
drupal_flush_all_caches();
?>

così mi ha eliminato tutti gli errori e ho potuto eseguire il cron, ma nel frattempo mi ha disabilitato le notifiche di aggiornamento.

Ho anche alzato la variabile max_allowed_packet, con il modulo Drupal tweaks, da 32mb a 60mb senza risolvere il problema.
Come posso procedere?
Ringrazio anticipatamente
Alessandro