Next button disabled when viewing previous slides

Most of the slides in my project have animations.  I want the next button in the player disabled until all animations have completed, so I have set triggers to disable the next button when the timeline starts and set it back to normal when the timeline ends.  The slide properties are set so that the learner will "Resume saved state" when revisiting. This is because I don't want the learner to have to watch all the animations again when revisiting the slide.  When viewing the slides from beginning to end, the next button works fine.  However, if I press the previous button to view the previous slide, the next button is disabled permanently.  Is this because the timeline isn't running anymore since the slide is set to resume saved state when revisiting?  Is there a simple way to fix this?