I had a similiar problem with Vue 6 right after I reinstalled everything on my new laptop.  It wasn't Vue, it was Poser 6.  Go into the Edit / General Preferences dialog and click the Misc tab.  Make sure that "Use External Binary Morph Targets" is not checked.

You may have already done this, but it fixed the problem for me.  There's also a limit to 1 dynamic cloth item per Poser file when importing to Vue (for me at least).  I always run the first dynamic cloth sim, export the completed sim object as a wavefront .obj file, delete the original, then load the .obj back in.  The only downside to this is that is can have some texturing issues, but I usually use Vue to create textures anyway, since Poser MAT file textures eat up Vue memory resources.

Like I said, you may already know all of this, but if not, I hope it helps.

Darkwolf

Quote - Well I'm running XP home and my graphics is an Nvidia 7300 gs with 512 RAM so it's similar to yours Bruno which is odd!
I mean I "can" use the shader tree but I have to purge memory constantly.

I've done a check and my background stuff is using roughly 500 Meg of RAM which leaves just 1.5 Gig for Vue, so if I put another Gig in, Vue should then have 2.5 Gig to play with, right! 
So would 2.5 Gig be enough to not have to purge all the time or is there still a reason why vue isn't freeing the memory, why can't they automate the purge memory thing!!!??

Okay, here's some advice from an old computer tech.  500 megs of RAM being used by the backround stuff is pretty high.  I'm running a fully loaded laptop with only 512 RAM (shared with Video).  Typically my background apps run between 250 and 300 megs, and I need to cut down on some of them.  You've basically got far too many background apps running.  Also, another thing  you can try is to raise your virtual memory settings on your pc - it'll run very, very slowly because the system is using part of the harddrive as memory, but it helps get rid of the out of memory errors.  To be honest, I don't bother with the Poser shader trees.  I can do much better by editing the textures in Vue because I have more control.

Hope this helps,
Darkwolf