i am using Vray,
i think figured it out, i did the teapot test you suggested,
and lured 2 things.
1- the distribution maps path was not properly defined as a network path, once i fixed it the teapots rendered fine.
2- my slave computer has less memory and i guess that is a problem in my bigger scene. i lowered the trees density and they did render.
soon the slave computer will be upgraded from 8 to 16 GB memory and then i'll try again.