Growing export time in imovie8. PLEASE HELP

I started with a 6 hour export time, but it keeps growing. Now currently at 15 hours. It just keeps growing and not progressing. The original data was downloaded to my computer in MTS from my sony camera. Imovie couldn't recognize it, so I converted it to Mp4. Could this conversion have something to do with the problem. My other movies seem to export okay. I'd appreciate some help, as I really need to get this project onto a dvd.

Thanks