I've been working on this pregnant model. I'm trying to create a set of magnets, so that clothes will be able to conform to pregnant models. Anyway, when I started rendering I got that weird line across the stomach. First I thought it was the lighting. But as you can see in this pic, she is lit from below as well as above. Then I thought it was the texture on the biker shorts so I got rifd of it and just left the shorts transparent. Then I thought maybe it was the shorts themselves. Removed the shorts and the line was still there. Then I thought maybe it was the magnet. But magnets don't cast shadows. Then I thought it was a texture problem. Nope. I'm at a total loss here.

Attached Link: http://www.bbay.com/anton

By looking across the parimeter of that area it seems that your linr is a shadow/highlight issue. Check to make sure the highlight color is black and set to zero.

I think your model looks great!! Especially the hair. Which hair is it? The bra and panties look more real with that tummy. Nice work!

Also check that the transparency is true black and white. If there are shades of grey, that can cause unwanted marks.