I see you’re using 10.8 as well, I wonder if Mavericks would change anything.
Yes, it looks like a 10.8. / Nuendo 6 thing. I have N6 playing on a 10.6. system -no such crash. And N5.5. on the same 10.8. works fine too. I thought aboiut updating to 10.9…but I use the same 10.8. system to play PT10 with Artist Control (working rather ok) and hear much bad things about ProTools and Eucon on 10.9. …that I do not dare to update at the moment.
Oswald