The federal health care exchange at Heathcare.gov has accidentally enrolled thousands of applicants in the government's sex offender registry, the latest of many technical failures to hit the troubled site. According to several senior officials, since the exchange went live on Oct. 1 around 40,000 individuals looking to buy insurance have instead been listed on the National Sex Offender Public Website (NSOPW), a searchable database of rapists, molesters and others convicted of sex crimes. The mix up was first discovered by people searching for sex offenders in their neighborhoods, only to find their own names. Administrators are uncertain how such...