I'm having a little problem using Kontakt 4. It works, but each time I load an instrument I get the spinning beach ball, it turns red in the Force Quit window, and then about 3 minutes later the patch appears and VE Pro responds again. Quite odd.
I'm on 10.5.8. using Pro Tools 8.0.1 I had previously been at 10.6.1 and PT 8.0.3 but I had to revert after having all my audio drives turn into "not a valid audio drive" in Pro Tools. I'm on a 2x2.66 Ghz Dual Core Intel (January of 07), and I'll be buying a new 8-core as soon as Digi approves a version of PT for Snow Leopard. I think updating my OS, my Pro Tools and adding VE Pro and Kontakt 4 all at the same time may have overwhelmed my (slightly) old computer.