I had that same problem once, a few months ago. I can't remember what I did to fix it. Thats not much help. I would try the following:

THISFORM.Refresh() in the form.

Toggling the TreeView's Visible property in the FORM.Init Method.

Selecting the first item in the tree. tv_tree.SelectedItem = tv_tree.Nodes(0)
I can't remember if that was tv_tree.Nodes(0) or tv_tree.Nodes(1) for the first node

Well, good luck.

Rob.