I made a very curious observation: On my old Windows 7 PC the arduino 1.6.5 installation produced the crashing version. Now I tried the same IDE (1.6.5) on my company-laptop and, don`t ask me why, there the example runs perfect ... crashfree the whole day. At home I meanwhile have a new Windows 10 PC, and yesterday, full of expectations, I installed the new arduino 1.6.9 IDE but I had no luck, the HelloServer example crashed again.
The big question is, why does the 1.6.5 Arduino IDE produces a working binary on one PC but fails on another. May be it`s the same reason why it don`t work with 1.6.9 ... I have no idea. Thanks to everybody for helping hints. I will search for the reasons and I will report the results here.
Dear Ehler, did you got some new insights in the meantime ?
friendly regards