For a real explanation : http://en.wikipedia.org/wiki/Three-body_problem
It's a typical chaotic system. Over the short term everything looks and behaves VERY stable, but every 10 million years or so things align juuuuust right and some major shift suddenly happens.
I haven't thought deeply, but a quick check of the Sun-Moon-Earth system seems to disagree with this.
For a real explanation : http://en.wikipedia.org/wiki/Three-body_problem
It's a typical chaotic system. Over the short term everything looks and behaves VERY stable, but every 10 million years or so things align juuuuust right and some major shift suddenly happens.