Why is my hair not growing back?

It was about November or October 2009 when I started using the Nioxin System #2. It came with 3 steps. The shampoo, the conditioner, and the scalp treatment. My hair has been fine. I just wanted to try out the product to help out my scalp, but after using it for a couple of weeks my hair began to fall out. I didn't notice it at first, but then I was losing so much hair. It is now mid April 2010 and the hair along my hairline is beginning to grow in, but the rest of my scalp isn't growing in. Is this permanent? Are my hair follicle permanently damaged? Can Nioxin cause permanent damage to my hair and not let my hair grow back?