H.264 Export Crash

Hey everyone, I’m new to the community and new to blender. After spending many hours following tutorials, I made a very simple visualizer. All I want to do is export the animation with an alpha channel so I can key it out in final cut (I know Blender has a compositor but it does not allow me to set the in and out points of the movie clip). Everytime I try to export the animation as a H.264 quicktime movie Blender crashes immediately when I hit render! Has anyone else had this problem?