As it happened, I was using my headphones yesterday while working on the hibernation problem, which made it easier to recognize when the sound card was activated and when not.

Interestingly, I got the distinct impression that the sound card came back on without problems right after restarting from hibernation mode, but that it got switched off / deactivated / whatever shortly before the process was over.

Is it possible to save all the screen output during entering / leaving hibernation to a file? I looked at the system log, but it doesn't seem to contain anything significant.