strange belabour - audio - video playback

I have a really strange belabour running c7.5.2 under Mavericks 10.9.2 and MR 816x

  1. When I open a project there is no audio sound, nothing, looks like everything in muted, the only solution I found to fix it is open any midi track and change something in this track, let’s say move a velocity controller or a midi note, after that, everything works perfect, any idea about this issue?

  2. And I have this strange pop up after a few minutes (Waiting for video Service), after that I have no more video playback in my cubase, I have to restart it.

Any Idea?
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