Vers. 1.8 stable, Drupal 5.2, PHP5/MySQL5. This is a db that was upgraded sequentially from 1.4. I get an error (code 24 – cannot connect to db) when trying to sync users to contacts. I have double-checked the CIVICRM_UF_DSN settings and they are correct. And other functions work fine, can add and edit users, etc., so obviously CiviCRM is finding the Drupal database.