weird lines in render

Hey there! i’ve got this weird problem:

There’s these wierd lines in the back of the neck. In the blender internal renderer the image turns out fine, but in yafray, these lines show up. they also turn up in 3d view. and i don’t think it had anything to do with my modeling
:confused: anyone know how to get rid of them??

http://img136.imageshack.us/img136/1707/linethinggw2.jpg
http://img175.imageshack.us/img175/538/linethingmodelsu1.jpg
http://img118.imageshack.us/img118/743/linethingrendertk7.jpg

have you tried to recalculate normals outside (CTRL-n in edit mode)?

otherwise Ive no idea

omg, its that simple?? i’ve been trying to solve this problem for a long time. why didn’t anybody tell me in the first place
well thanks a lot!! :D:D:D:D:D

HEHE dont feel bad i spent 2 days trying to figure out on one Coke bottle tutorial why i could not get weird banding to go away … it was corrected by ctrl-n