Oh Robyn, thank you for going to the trouble to test it for me!  For testing purposes I just had one IBL and another light for shadows but I first came upon the problem after rendering out a final image that took 4 hours or so.  So I made another render without the IDL to salvage it.   But it bugged me and so I wasted half a day trying to figure it out ;)  At least now I'm sure it's not something I'm doing.  So I think I'll stop modifying the texture as well - as you can see that has its problems too.
I didn't use anisotropic because bagginsbill recommended against it except for very specific instances which I've now forgotten what they were.
And yeah Poser Pro 2010 rocks!  And you're right, very little hair will look good now with IDL and GC since most of it has burned in specular.  I shudder to think what they will look like in Lux.  So now I'm sleepless and playing in the Hair room since that's probably the way to go.
Now if only carodan would share some tips on growing such natural hair as in his images :) wink wink nudge nudge