Are you growing the hair on a skullcap or directly on the figure? I've been messing with hair all week and have seen this same problem. It seems to be related to hair that collides real early with some body part or that starts inside the body. --such as around the ears. By VERY carefully positioning the skullcap so that it doesn't ever intersect with any head parts, I've sometimes gotten a decent render. But you have to ignore the way it looks DURING draping and wait to see what it comes down to afterwards. Turning off collisions also seems to help...but may result in some pretty weird looking hair in its own way.... Don't take my word as gospel, though. I'm still groping through this stuff myself...