Yep -- the hair usually has vertex colors - Try going to the hair mesh tristrip in the NIF and highlight the NiTristripsData line and check in the Block Details for the Has Vertex Colors Line and change it to no - that should take care or the problem - if not also look at the NiMaterialProperty node and in the Block Details window make sure the Ambient,Diffuse,Specular,and Emissive colors are not set to a bluish-green color and if it is change them to match one of the other nodes material properties.