In Maple 7.2, when I delete a node, most of the tree collapses. This is incredibly frustrating. It's less prone to do this if I delete with Ctrl-D or Rightclick>Delete than if I delete with the Delete key, but it still happens a number of the time.
I use Maple for organizing IT trouble tickets, and when the tickets get completed, I delete the node I have for that ticket. About half the time after that, I have to go through and click back open all the branches I had open.