that sounds decidedly odd!
I don't know what you've tried but i'll offer a few suggestions in the hope that one of them might help:
Firstly - RAW or JPEG? And what converter? And regardless of the D200 screen (my Canon 5D has a definite green cast on it's own screen - it's horrible) is your monitor calibrated?
Have you tried fixing the white balance to match the light you're shooting in or is it on Auto? Have you shot in manual only and used the histogram to check exposure. Is it with flash, without flash or sometimes either?
AND have you tried using a different camera to see what that does? ( or a few different ones)
It could just be that that is what Nikon intended for such shades (of course now i've posted this a D200 owner will come along and tell you exactly what is going on!
)
If it really isn't fixable then you may be able to create a photoshop action (if you use it) that corrects the purples to the right shade...
hope something in there turns out to be useful!