may be someone here knows about that...
Fortunately, I was able to fix my windows xp account (not machine, only my account - with other accounts there was no any problem) to play the sound (DV stream) again. I had to remove this key:
After first starting of WMP this key was recreated and playing of the DV stream was ok.
Unfortunately, googling gives no knowledge about this key. What this could mean and why this key blocks building of the correct graph?