Well I use Bryce 6.0
And my laptop has a single core P M740 1,7Ghz, WinXP,1GB,Geforce Go 6800

I just had to abandon that project and start a new one.. no other choice. I think it was something object related because I added all the objects to the library and then into a totally new scene.. same happened. But i didnt have patience to go that far that I woud have tried to discover which object was the reason.