No sound at all in Cubase 6.5

I have the same problem in Cubase LE Elements 6 64 Bit on Windows 8.
Creating a new project in Cubase is no problem, there is sound.
But no sound with old projects and no sound after import of MIDI file.
Tried different ASIO drivers, now using AIO4all v2.10.
Devices->DeviceSetup->Ports->Out:HD Audio output 1 and HD Audio output 2, both visible and connected.
Devices->DeviceSetup->ControlPanel: Realtek HiDef Audio output activated, BufferSize=192 sample
All other midi editors work fine.
Can anyone help me?
Thnx