Absynth and Live 5 making strange noise

[Rik]

I am running Live 5 on a Powerbook 1 Ghz and since I've upgraded to live 5 my Absynth is making strange sounds. You can hear and play the chosen preset in the background overlayed by a very loud distorted sound. Sounds a little bit like a buffer underrun noise. The same happens in VST and Audio Unit Version. If I go back to Live 4 all is fine. All other Plugs work well. Whats the problem?