Hi. I have a similar problem with a QuadroFX 750 running on a dual Xeon (SMP) and drivers 4496, but NVIDIA is either ignoring my requests or they do not know what's going on. It does not happen on my single processor GeForce4 4400 card.
I have done some testing and found that setting
__GL_FORCE_DIRECT=0 in the environment
will fix the problem.
(Using bash: export __GL_FORCE_DIRECT=0)
Now, I do not know what that flags does, yet.