Thank you nomuse,

I saved my work as a scene file. It saves as *.pz3 and also the *.pmd and the *.dyn files are saved.
Then I tried to import this file into another scene. That worked perfectly well before I installed SR2 and it works still in P6.

Following your workaround I still have a problem. How can I set the timeline to zero without loosing the pose of my character?