** FILE ** An unidentified person leaves Enron Corp. headquarters in Houston at the end of the day in a Jan. 22, 2002, file photo. The successful convictions Friday, July 13, 2007, in Chicago of Conrad Black and three other former Hollinger International Inc. executives signaled the latest in a series of triumphs by government prosecutors in an Enron-inspired crackdown on corporate crime that began five years ago this month. (AP Photo/Pat Sullivan, File)