What exactly was the nature of the playback trouble?
What are the settings of your problem sequence?
What export format / codec did you use?
What was the method of your failed playback (software, hardware)?
The first few pictures would play fine, and then, the pro pics start, and they all look bizarre...like a kaliedescope. They get out of time with the music.
We saved as a 4/3, 16/9, and as a quicktime.
As John Smith suggested, what is the pixel dimensions of your photos?