Errors removing rows from treestore

[Matt Bragano <maestro485 comcast net>]

After much help, I've successfully implemented a TreeModel with a 
TreeModelFilter.  However, I've noticed that if I expand a node, 
collapse it and expand it again, the contents are "doubled".  That is, 
if the expanded row contained items A and B, on the second expansion the 
items in the row are now A B A B.

I tried using a model column flag to determine if the tree had been 
expanded once prior, but with no luck.  Now I'm trying to simply remove 
the child rows in the on_row_collapsed() method like this:

void on_row_collapsed(const Gtk::TreeModel::iterator& iter,
                                     const Gtk::TreeModel::Path &path) {

Gtk::TreeModel::Row row = *iter;

const Gtk::TreeNodeChildren &nodeChildren = row.children();

Gtk::TreeModel::Children::iterator child = nodeChildren.begin();

while(child != nodeChildren.end()) {

   child = refTreeModel->erase(*child);  // this causes errors

}

}


The problem is that every time the while loop is executed I recieve this 
error:

Gtk-CRITICAL **: gtk_tree_store_remove: assertion `VALID_ITER (iter, 
tree_store)' failed

Any ideas as to what is the problem here?  Or is there a better way to 
work around the doubled-up rows I'm running into?

Thanks,
Matt Bragano