Menu items out of sequence

Hi - hoping someone can help.  I have a scene where a number of slides are out of sequence in the menu in the player to what is listed in the scene slide numbering sequence.  They are running sequentially according to the player triggers but because they are not listing correctly in the menu in the player it is jumping all over the place in regard to completing the navigation list  (highlights are all over the place).  Is there something in the background which could be affecting this.  I have checked the slide properties and these seem fine.

I have also set the slides to be advance by user - but they are advancing automatically.    Could the slides be corrupted??

Any advice you can provide would be much appreciated.

Thanks.  Cath.