Unfortunately we believe the issue is with the large size of your project. It is very important to remember that project sizes are not infinite in iClone 6 and regular crashes with one particular project is often the result of the project reaching a size that iClone can no longer open and maintain stability on your computer. The simplest solution if the size or complexity of the project is the problem, is to try to break the project into two or more smaller projects or reduce the complexity. This way you should not encounter the issue again. You can then edit the rendered videos together afterwards.