Topic: HELP : Problem RME Babyface e Cubase 6.0.5

I buy RME Babyface 2 days ago.
Babyface silver edition.
I install the last drivers and firmware and all it is perfect.
The card works fine to listen internal audio, mp3 ecc but i work with cubase 6.
When i start to work in cubase i have this situation:
I make a new project in cubase and I make use 2 or 3 (so not many more) VSTs/samplers/VST effects or a VST synth such as Kontakt or Gladiator synth and the VST performance DISC meter (activated within Cubase with F12) jumps to 100% for a very short time - perhaps just fractions of a second and my cubase freeze..stop to play..crash and close automatically.
When i make a final mixdown the status bar arrive in 50% and cubase crash and close automatically!
It's a very bed situation!
I work with another soundcard last time and have no problems...2 days with my babyface and it is impossible to work with it!
I try to change buffersize but with no result.
i try to install last riginal cd drivers 1,61 but with no result too.
Please solve this problems, i don't want to give back my babyface to my shop ((

I have Mac osx 10.6.8 snow leopard
New Imac 21" I5 quadcore with 4 gb Ram ddr3
Hd 500gb - 7200
Daw : Cubase 6 elements 6.0.5 (Original version)
Drivers of my babyface : 1.66
Firmware : 185