animate keeps crashing when I try to export

i have made a 4 minute animation which barely has any ketframes and has baout 10 layers. Whenever i try exporting it as a mp4 or wav file it keeps on crashing at 70%. The swf gets made but not the mov file. i have quicktime and i tried exporting a 20 second animation that worked perfecty. i really dont know what else to do because there aren't many vectors as well. if anyone can try downloading it for me and sending it back that would be really helpful or tell me how to fix this problem. i have been working on this since 2 months so i can't redo it either.