MIAMI (Reuters) - Guantanamo war crimes prosecutions of five prisoners charged with plotting the September 11 hijacked planes attacks will be delayed by two months because of lost files caused by Pentagon computer problems, U.S. military officials said on Wednesday. A weeklong pretrial hearing had been set to begin on Monday in the death penalty case against Khalid Sheikh Mohammed, the accused mastermind of the attacks, and four alleged co-conspirators. The judge overseeing the case postponed the hearing until June 17 at the request of defense lawyers who said three to four weeks' worth of their confidential work files had...