In this study, each HPS and pre-HPS subject will be treated with a commonly used antibiotic called "norfloxacin" (approved for use in the treatment of gonorrhea, prostatitis and urinary tract infections) for a 4-week period. In order to ensure that any observed improvement was indeed due to norfloxacin, each subject will also be treated with a separate 4-week course of an identical placebo. There will also be a 4 week wash-out period (no study medication/placebo) between the 2 courses of treatment.