Scenario Name:                            SystemDownRentVideo
Participating actor instance:        Bob: Customer, Joe: Cashier

Flow of events:                             1. After searching the stores for 20 minutes, Bob decided to rent a video.
                                                      2. Bob pick up his video, "American Pie", and comes to the checkout stand and hands the video to Joe.
                                                      3. Joe took the video and request for Bob's membership card.
                                                      4. Bob hand over the membership card.
                                                      5. At the monitor screen, Joe start the system into checkout mode.
                                                      6. Joe pick up Bob's membership card and scan on the bar code.
                                                      7. System came back with an error message saying that Bob's account is inaccessible.
                                                      8. Ian restarts the system and tries the whole process over.
                                                      9. The system still shows the same error message.
                                                    10. Ian did not know why so he phones the manager.
                                                    11. Ian asks Bob to go to a different checkout stand.
                                                    12. Bob takes the video and goes to the checkout stand.

Object Diagram: