I´m having the same problem in 3 different lightscape files, I initialize, calculate, everything seems to be ok, but when I render soe parts of the geometry just disapear!
I´ve tried all my knowledge, played with near and far cliping plane, tried to see if the scale is ok, tried to atach boxes in max, tried to export and initialize just one part of the file, to reexport all file, to play with minimum mesh size, but nothing solved the problem.
We have to finish this work urgently, and if the problem doesn´t solve I´ll be crazy!!!
Please anybody help me!