yep, I get the spinning rainbow in 10.4.10 as well, quite often.  glad to know they're working on it.
in regard to poser interactions, would agree with GK to try saving the motion as a pz2 file, if the pz3
file is slow-loading in c6pro.  if the default runtime in the poser 6 folder is on a remote disk,
that may slow it down as well.  I find c6pro is often asking me where the default runtime is,
then I realise I turned off the drive on which it's located.  works o.k. once I load the drive.