Apple Powerbooks and External Displays

I love my 17" Powerbook. When at home, I connect it to a 23" cinema display. Unfortunately, when connecting and unconnecting the external display from a suspended state, the Powerbook would occasionally appear to freeze. I believe that the state of the display hardware was confused. The machine was up, but simply had no active display. This problem can be solved by a change in usage pattern: I now ensure that the machine is awake before disconnecting the external display. One does not have to be logged in; simply pressing a key to show the login box is sufficient (if you require a password after suspension). Oddly, it appears that you may connect an external display without worrying about the suspended state.