Hi,
Sorry to be so slow responding to this:

I have Vue6inf 64bit with Vista; using the "Render Materials using Poser Shader Tree" does cause Vue to crash on my system :(

It's a new system with very little installed on it so I am surprised/disappointed at this odd behaviour. I have noticed that having Poser and Vue open together can sometimes cause either to crash.
It should not be a RAM shortage, there is 8GB.

I wonder if it is the video card, it is an Nvidea GeForce 8800GT with the latest drivers installed.

I know programmers can't predict every possible error, but you would think that they would put more effort into error trapping and giving useful error messages that can lead to identifying the problem; instead we get the usual useless message; An error has occured.
(no kidding, I wondered why the program had stopped working... an error... yes, that must be it!)
Sorry for the vitriol, but one can get very frustrated when thing don't work as they should :/