After consulting a Web site produced by the advocacy group Parents For Megan's Law, a parent discovered that a 51 year old man, convicted in February 1999, of attempted sexual abuse lived a few houses away from a school bus stop and within a quarter-mile of two elementary schools.  Anger exploded in Commack at a packed school board meeting attended by approximately 400 parents when school officials and parents found out that Suffolk police chose not to notify the district about a high-risk sex offender living in their area.  The district has notified surrounding school districts and moved four school bus stops farther from the offender's reported address.