[Simone Bellini]

first, sorry for my english. I have the same problem. but the reason is simple. but terrible: The newnew quick time for itunes film rent, every 10 min, try to check the drm in an open quicktime. After effects writes the .mov specification at the end of rendering, just before closing the file. The qt engine, when check for drm, think you have cracked the qt information to remove the drm. Change the permission of the file and this cause the rendering failure. The only actual solution is render a tga sequence and then build a quicktime.
Sorry for badnews.