Looking back, Mark and Cheryl Miller would have done a lot of things differently with their 13-year-old son, Matt. They probably would never have left Lenexa, Kan. They would have sent him to a different school, and they certainly would have chosen a different therapist. But most of all, they wouldn't have given him Zoloft. ''It's not a pleasant thing living with the thought that you had a hand in your son's death,'' Mark Miller told me recently. ''Making him take those pills was done out of love for Matt, but it was still the wrong thing to do.'' We...