Comment 17 for bug 520941

Maybe somebody who is seeing this could put together a simple project which can reproduce this and share it (from the descriptions it only happens on 'complex' projects, but perhaps something which re-uses just a couple of clips but does lots of transitions).

Providing devs with an sure way of reproducing your problem is always going to be the fastest way to get your problem fixed, particularly when there's so many potential variables. (of course there's no guarantee that everybody sees the same results, even with the same files, but even that would tell us something interesting).