Dokeos Conflict?

I'm hoping someone can help me or point me in the right direction. I'm currently using Drupal 6.13 in a multi-site configuration, one for my domain and two others for subdomains. Each site uses the same drupal code but has its own database. I am also running two separate phpBB3 installations (one for the domain, another for sub1) a Moodle installation (sub2), and Dokeos 1.8.6.1 (sub2). But I have encountered a very frustrating problem with Dokeos.

Dokeos works initially, and is located/accessed at

http://sub.domain.net/learning (though this is actually the same as http://domain.net/learning)

I can navigate through most of it, including the course reporting pages for any courses I create (though there is nothing to report) which is at

http://sub.domain.net/learning/main/tracking/courseLog.php?cidReq=SAMPLE100

but when I create a course, I cannot access the course page, itself, which is located at:

http://sub.domain.net/learning/courses/SAMPLE100/?id_session=0

Instead, I get a page in my Drupal site that informs me "The requested page could not be found." It seems as though Drupal is intercepting the page URL.

Has anyone encountered anything like this or know how I might resolve the issue?

Thanks for any help you can provide,
~Dogtag