QTR-Quadtone RIP

Why is the process of printing and setting up so different between Mac and PC? My PC prints 
with NK7 QTR are yellow and my Mac prints are yellow and purple? So a Mac need no 
calibration before you print? Weird. I have to say that I'm becoming very frusterated with QTR. 
i can see the potential, but it seems to be too much of a pain to deal with it. I find it strange 
that there is no real support for this product.

Any help is appreciated.

Brad