Hi Kim,
All of those items from the "previous slide" that you see animating off are just duplicated on the new slide. I have them set to animate off right when the new slide starts.
Take a look at the timeline for the slide and you should see a group called "previous slide items" or something like that. That will contain all of the items that are animating off really quickly before the new stuff animates in.
Let me know if that still doesn't make sense. If not, I'd be happy to hop on a screen share with you to walk to you through it. Just let me know.