Frame animations disappearing

I am suddenly experiencing a new problem with frame animations disappearing. When I open a page I see one frame of my frame animation, as I always have. But when I trigger the animation it disappears. This is happening on about half of the animations in my book. I have cleared the cache and restarted Interact Builder numerous times. This fixes a few of the animations but not all of them.
Is it safe to "trash" my Interact Builder program and re-download it? Will my project still be accessible if I do this?