If you expect that the data changes between activations, then you can add a Thisform.OleTreeView.Nodes.Clear before populating it, otherwise you can use the suggestions given to you by Naomi and Viv
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges