I've got the Quadro FX 560. The driver is version 184.108.40.206.
Another clue; sometimes if I switch from shaded to wireframe then back to shaded view, the hair will update itself one time, but never more than onece.
I use to do hair FX on this computer in the past but I think I was running Maya 7.0.... I can't exactly remember the version. The variables that have changes are just a few. I now have a dual monitor setup and I switched to flat panel monitors. Everything else is the same (double dual cores, 4 gig ram, XP pro sp2).
............ I just now updated my video drivers to the latest versions.... No change..