Part I will be a 2-week evaluation phase. In Part I, subjects undergo a diagnostic interview for symptoms and treatment along with medical, side effect measures, and neuropsychological tests (tests for memory, attention, and motor task skills). An electrocardiogram (EKG), a urine sample, and about 3 tablespoons of blood will be taken for laboratory tests. Women will have a pregnancy test. This part of the study is 3-4 visits. The time of the visits will be about 8 hours.