@cryzymelki:
Oh, yes, that's it! I tried to boot the wrong empeg :-). Just took the right one and it's booting perfect ;-).

@all:
I pressed on the connector of the hdd and it was ok, but this could be a random effect, maybe it was the same if I just tried to boot again. But if it works, shouldn't I see something in /var/log/messages (or such a file?) regarding hdd-errors?

Rolf