Can anyone give me a hint what I might need to do to get rid of the following problem?  I'm trying to make a render with the Rozhair and I've checked and double checked and triple checked and all the materials have all the same nodes except for transparency value but I can't for the life of me figure out how to get rid of these black stripes running through the hair when it renders. You can see in the attached image what I mean.  I'm pulling my hair out on this one, the black stripes even show up in the material preview but I can't figure out why.  If I remove transparency from the primary "hair" material the black areas disappear from the preview but still show up in the final render.  In fact any material I up the transparency value on becomes black in the render. Can anyone suggest something to try please?  I thought maybe the background colour was the problem but changing it to whatever has no effect, tried the scene background colour and also the transparency background in each of the material nodes, most importantly the trans map one, all to no avail. This is driving me insane, I can't figure out why upping a material's transparency would consistently turn it black.