If you have projects which no longer open send them to us and usually we can fix them (one or two things might have gone missing though).
This bug has cropped up from time to time recently and obviously it's one we really want to fix. However nobody seems to have been able to reproduce it, and I've never seen it on my own computer. This makes it extremely difficult to fix. If you can make a backup of your project and find a sequence of steps that always breaks it, that's great - we can probably fix it immediately if anyone can get it down to that.