AJAX :: Mysql_query() Call Returns 'access Denied' Using XML HTTP Req Object

I am getting an error to a mysql_query() call: Access denied for user 'SYSTEM'@'localhost' (using password: NO)' in path 'C:PHPClassesMySQLDbClass.php' at line 1078 This is coming from using a XML HTTP Request object (AJAX) to send form data to the server requesting my DB records interface script page, ajaxRecordsInterface.php. In using PHP sessions, I have no problem going from a logged-in-select-activity PHP document to an activity controlled by a PHP document that does records interface. But apparently an XML HTTP Request object has a different session than a PHPdoc-2-PHPdoc session. Is that so?

Here is MORE DETAIL: I am building first a version of a web-based database interaction using MySQL that does not use page reloads, so that means I am using Ajax/XML HTTP request object/Javascript (later I build the version that does script-free page reloads to show db updates/refreshes). I have no problem with login whose first PHP document gets user information and presents it, as well as a menu of links to how to interact with the DB. One of the options is to add/edit/delete student records.

In the PHP document which is the DB records interface, I have a scrollable HTML table at the document top with one table row for each record. Below it is an empty form, whose fields get populated when the user clicking on a record in a table row. Note that all fields for the records in the table rows were delivered as a Javascript array with a maximum of 50 or a 100 contiguous records in the MySQL table. (More optimizations may be done later, such as creating a Javascript array as a "cache" of the last 20 or so selected records.) I don't have problems making mysql_query() calls in a series of PHP document requests. I call session_start() to get session variables, one of which is a serialized MySQLDatabase class object which I unserialize to get the object again. The problem is the XML HTTP Request to a PHP document designed to interact with it is a different PHP session from a page-to-page session.