Choppy transitions when converting to MP4 [Resolved]

I created a video slideshow that looks great when I play it in edit mode. However, I have tried to convert it to several different MP4 variations and each time many of the transitions are choppy and/or have horizontal lines going through them. In addition, some of the backgrounds don't appear all at once (e.g., the left side appears, then the right side comes in).
Please help!