Hmm.. I tried Carrara 7.1.1 and it crashed on my first render, It was a simple scene with a m4 and a hair. I think it can be something with the transparency, because one of the cores just stopped on the hair, and when the other core was done carrara crashed and shut down. Or perhaps its a amd dualcore problem, Im on a amd athlon 4200+ with 3.25 gig of accessable ram. Other than this C7 felt sluggish on my system. Never had this sort of problem in C5, just the "run out of memory" problem and I guess theres just not much they can do about that. Hope you get things sorted out, perhaps C7 just like new systems better.