How To Clear a Listbox Using an ArrayList DataSource?

How do I clear  a Listbox that uses an ArrayList for its DataSource?

If I try MyListBox.Items.Clear I get an exception telling me I can't change 
the listbox's ItemCollection if the DataSource is set.

If I try MyArrayList.Clear I see that the array is cleared but the listbox 
is not. If I then add new items to the array they do not show in the 
listbox.

So how do I clear a listbox if the datasource is set?

-Andy