From Yahoo News and the AP:
The Navy temporarily lost communication with a submarine off Florida's coast and sent ships and aircraft to search for the USS San Juan (SSN-751) before the vessel was contacted early Wednesday (March 14, 2007), military officials said.
You can read the whole story at http://news.yahoo.com/s/ap/20070314/ap_on_re_us/missing_sub_1
The San Juan is part of the USS Enterprise Carrier Strike Group operating off the Florida eact coast.