I was having the same problem… the menu button would activate the timeline… play it through, and then at the end play it again. Essentially, when you previewed the DVD’s operation, you had to hit the “end action” twice to get the timeline to end and go back to the previous menu (as instructed in the properties of the timeline).
Solution for me: I had put “overides” in the properties of the buttons… I clicked and deleted these and the timeline playing twice ended and the end action went back to the previous menu (as instructed).
Hope this helps.