I've had this problem as well. The particle instancer is not very good and fails even with a small number of objects randomly or simple won't render specific frames??? I haven't seen anything about Maya4 that leads me to believe that it will be any better.
What I suggest is that you write a MEL script to puts expressions on your duplicated objects to follow the particle system. It's sounds like alot of work but it is certainly going to be more robust than the instancer and will actually give you more control.
BTW instancing objects doesn't do much good when it comes to rendering. They may be instanced in your program but when they are rendered they are turned into actual geometry. This is a big problem if they are nurbs because they turn into polys in the render and generally take up alot of memory.
---a note from our sponsor---
Have you tried searching highend3d?
www.gmask.com
