Hey achow,
thanks for your support.
I've tried it. But its the same issue. When i try to unlock my wallet with the right passphrase, the bitcoin core crash with the report:
bitcoin-qt: wallet/crypter.cpp:198: bool CCryptoKeyStore::Unlock(const CKeyingMaterial&): Zusicherung »false« nicht erfüllt.
Abgebrochen (Speicherabzug geschrieben)
The last two lines are in german. Translated it means: Expression "false". Storage access failure.