Browser closed when hitting delete in weekly template

I was using Safari on a SNow Leopard Macbook Pro, all patches uptodate. I wanted to define a task on Mon, Wed, Fri, so I did it on Monday, dragged across to FRiday to create five instances. I then selected the Tuesday instance and hit "delete" figuring it would remove the task. Instead the browser window closed.

Is this a bug/feature/user error?