Particle-system crash 2.77a

I use Blender 2.77a.
In the scene there are two particle-systems - each with 1000 particles and 15children.
Every second time i try to render the scene Blender crashes. Every other time it works…
i am rendering in cycles with amd r9 390 on a win10 machine.
Any ideas what is wrong? A bug in 2.77a?

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