Audio out of sync and video out of order

Hello all, I have tried three times to create a video with this program (30 minutes long and 3 tracks of audio, pictures, and video) and during preview, everything is 100% in sync and in order. After Exporting (which takes roughly 30-45 minutes) I view the video and the clips are out of order, some repeated, and the audio is delayed about a full second. Does anyone know why this may be happening or how I might fix this?