Juan,
as already notified two times with RC5, the defect remain identical in RC6. The typical case is when after creating a new preview, and done an operation test in it, I try to close it with context menu (with right mouse button). Almost everytime PI crashes without a lament. I'll put here other cases if I find them, but this is largely repeatable.
Thank you in advance, I'm a software developer and I know how hard is to manage such a large project.