Treeview in Combobox moves after node in treeview is selected

[Aaron]

I have a treeview inside of a combobox and once a node on the treeview is selected, the treeview and the box that is containing the treeview 'detach' from the combobox and move about an inch and a half down the page and about a half an inch to the right before it closes.  I have used this combination of controls a few times in my app and it only does this in this one instance.

Is there a property I need to set so that the dropdown of the combo always starts and stay directly below the combobox?

Thank you for any help you might have.

Aaron