Limited List of Users in Post Author pulldown

I have done a recent install of WordPress 2.1.3 and imported a postnuke system into it. This was imported from a large community (4200+ users).

When a user submits a post (all are Contributor level except 3 who are admin), the post is placed in drafts. When an admin “approves” it by publishing it, the author becomes that admin. Ok – simply change the author to the correct user.

Here is the problem – 4200 users and only 25 show in the Post Author list.

I have looked at the code for the get_editable_authors function from the admin-db.php file that would generate the list and nothing in there suggests why there are such a limited number. I am looking in the DB issues in case the import was the issue, but any thoughts would be very appreciated.

Thanks