Movie Maker reverting to a single type of animation

I am currently creating a 'movie' using photographs of an overseas trip we undertook.  I have downloaded photos, giving different animations to suit the photos, different transition times, and different times for the photographs. 35 minutes into the project, for the second time I have discovered that ALL photos have reverted to Zoom in to Centre!!!!!  Despite saving the project as I am 'going along' I am unable to bring up my edited version and it looks as though I will have to start all over again for the second time!  How do I prevent this happening again, and what is the best way to save it?