arumbus.. that's a seriously easy fix(at least for a network guy).  what luxrender does for a network render is for the master computer(the one that you start the render on) to be able to send all the texture files to the slave computers; and for those slave computers to be able to render your scene and then send a temp file of those compiled samples back to the master in order to be added to your scene.  In order to do that; the master computer has to have read/write permissions for the luxrender directory on each of the slave computers; and, for the slaves to have read/write permission to wherever it is that your scene is being rendered(the place where lux is writing all the files for the render.

it sounds more complicated that it really is.  are you using windows7?  if so, are you using the homegroup option for your home network or are you using an oldschool workgroup like i do?