CS6 strange frame rates at exporting a QT

Hi,
I am new to the forum an quite new to PP CS6.
I was editing a project for the first time with 400 mts from a GH2, 23,97fps
Everything went fine except export. H264 for my client's vimeo preview
was perfect. Exporting a ProRes HQ master brought up strange frame rates.

This is my setting (sorry German localisation)



The frame rate of my exported QT varies is a strange way.
here#s a sample of 23.43fps but I had also 23.621



Thanks for help,
best, Cler