Essential Suite 188.8.131.52
When you call Nodes.Clear on a TreeNodeAdv, and the SelectedNode is one of the nodes that is removed from the tree, SelectedNode is not changed. That is, it still refers to a node that is no longer in the tree.
Just an FYI,
This issue has been fixed in version 184.108.40.206. We have made a lot of changes and enhancements to the TreeViewAdv control since the 1.6 release and I will email you download instructions to a new build which should be released next week.