CCK Cache Error message after updating DB , please help troubleshoot

Hi,
I upgraded a full site from drupal 4.7 to 5.1.
I make full use of cck and views.

All went well except for this message while updating the database after cck was updated:

# user warning: Table 'xmysite-drupal.cache_content' doesn't exist query: SELECT data, created, headers, expire FROM cache_content WHERE cid = 'content_type_info' in /big/dom/xmysite/www/includes/database.mysql.inc on line 172.
# user warning: Table 'xmysite-drupal.cache_content' doesn't exist query: LOCK TABLES cache_content WRITE in /big/dom/xmysite/www/includes/database.mysql.inc on line 172.
# user warning: Table 'xmysite-drupal.cache_content' doesn't exist query: UPDATE cache_content SET data = 'a:4:{s:11:\"field types\";a:5:{s:13:\"nodereference\";a:3:{s:5:\"label\";s:14:\"Node Reference\";s:6:\"module\";s:13:\"nodereference\";s:10:\"formatters\";a:2:{s:7:\"default\";a:3:{s:5:\"label\";s:7:\"Default\";s:11:\"field types\";a:1:{i:0;s:13:\"nodereference\";}s:6:\"module\";s:13:\"nodereference\";}s:5:\"plain\";a:3:{s:5:\"label\";s:10:\"Plain text\";s:11:\"field types\";a:1:{i:0;s:13:\"nodereference\";}s:6:\"module\";s:13:\"nodereference\";}}}s:14:\"number_integer\";a:3:{s:5:\"label\";s:7:\"Integer\";s:6:\"module\";s:6:\"number\";s:10:\"formatters\";a:5:{s:7:\"default\";a:3:{s:5:\"label\";s:4:\"9999\&quo in /big/dom/xmysite/www/includes/database.mysql.inc on line 172.

It never did the message again, and the site seems to work fine, but maybe this is significant problem and I will experience troubles. I checked in phpmyadmin and cache_content do exist.

Cordially,
Brakkar