WASHINGTON - Prince William County's crackdown on illegal immigration could be having a chilling effect in some local schools. "It certainly is an anomaly that we would have a little more than 600 fewer students in the ESOL (English for Speakers of Other Languages) program than what we had at the beginning of the year," says Prince William County school spokesman Ken Blackstone. "We are always concerned when there's anything that would create an apparent anomaly like this, a drop in enrollment." Many of the students who left the school system left after the county's crackdown on illegal immigrants started...