Ah ah!
You see, erase event doesn't get rid of the event, it just makes it go away while you are on that map. It reactivates when you leave, so the next time you come in, it starts again.
To "delete" an event for good:
Add a self switch to the end of the cutscene:
Make a new event page:
Add the following condition to the new (second) event page: "Self Switch: A is ON" (or whichever self switch you used in the first event page, in my case it was A)
Now press OK. The event will now only happen once.
End result:
http://www.mediafire.com/?6hn9heh8ldh9b7s