Clear Treeview for refresh

I am using the below code to refresh my tree and it works until hit refresh on a grand child

Code:

---

For Each n As TreeNode In Me.tvwMain.Nodes
                n.Nodes.Clear()
            Next

---

If I refresh on a parent or child it work great, but as soon as I click on a grandchild it crashes. I say it crashes because the icon for the parent changes and when I click on plus to open it it reloads the whole tree and then it all works fine and has the correct icons/folders.

So how do you refresh even when have a grandchild open? Should be able to refresh no matter where you are in the tree.