It's not just the thread starter that prevents an article being inserted. Each usenet article has references to every post that was posted before it. An article will only be placed in to the forum when the post immediately before it is available. If it didn't work like this you would get posts appearing as replies to a message that doesn't exist. Very confusing! When you first start pulling news this occurs a lot due to the fact that many of the articles will have expired but replies are still there. As time goes on the surplus will expire from the usenet_article table and the number will reduce. Provided your news provider gets all posts, you will get them too. I am confident this part of the script is working as it is the part I spent longest on to ensure all articles were collected and inserted when appropriate. An example is my dbforums site. It has been running long enough for the orphan messages to fall through the system and I now have about 800 articles in the usenet_article table. This is from 70 usenet groups. So that is the number you can expect after about a week of running (provided your expire is set to 5-7 days) in the control panel.

Let me know if this would explain the numbers you are seeing.

And you are you using the latest version right?