Since I can edit the .avi I was able to insert a single blank frame or a frame of my choosing as FRAME NUMBER ZERO.
This may be unacceptable to some that don't edit videos so ask Microsoft if they have another way.
Bob
I've inserted an .avi in my slideshow and after it plays, it goes back to the first frame before moving on to the next slide. The only information I found on this problem said that you have to get rid of the transitions to and from the slide. I did this, but it didn't fix the problem. The person who was troubleshooting this for someone else said that it did this with only certain transitions but the ones that worked for him did not work for me. I haven't found any other information, so if someone could help me, it's kind of urgent. Thanks.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic