I have a function in a separate class that updates the treeview control nodes on a form. The class has a reference to the tree control, but not the form. The problem is that if try to close the form while the function is updating, the form closes, but then reopens because the function is still referencing the treeview. Anyone know how I can keep this from happening? I've tried setting the object= nothing when the form closes, as well as the reference to the treeview, but it didn't work.