Hi,
I used the following in setting up my CRON job. The first itme I think I had a sapce and it didn't work. I also set it for 15 min. but changed it to 60 min. because they didn't like getting emails tht often from all of the forums.
GET http://www.mydomain.com/courses/admin/cron.php > /dev/null
Hope that helps.
Sandy