Document categories sidebox not working?

I added a new category and restricted it to type "document - product" then created a few test items.

When I FIRST load the home page I see the Documents sidebox, but it only has one blank field with a link to nowhere. If you click on ANY link, or if you just try to reload the homepage a second time the ENTIRE right column will disappear! The only way to get the column to come back is to wait a long time and then reload the page again. But again it disappears after loading another page.

ALSO I noticed the test category I created is showing and browsable on the normal category sidebox. I thought document product type categories would only show in the documents sidebox? I need this to work because I need two separate category boxes for the two sections of our store.

TIA for the help. I am totally stuck on this.

I have confirmed this also happens on a fresh, brand new install of Zencart. If I use product type "Document - General" it works just fine. But if you create one item using "Document - Product" it appears to bug out the whole site. Am I missing something or is this a bug?