Final case: The debugging of this state closed. No solution found with those machines in testing. I ended up with a fully new hardware architecture, a lot newer machine. Fully reinstall again, now on Ubuntu 14.04.2 LTS, 64bit. Fun fact, issue never again happened. Maybe candid camera was removed from room… damn, it was a bit frustrating haveing such insane malfunction with a normally working software. A week passed by, no issue anymore. Strange.
Thx for replies and tries in helping!