NEW YORK -- New York Times Co. (NYT) says it has shut down computer systems at its Manhattan headquarters, potentially making the newspaper publisher a high-profile victim of computer viruses that are ravaging corporate networks across the U.S. Toby Usnik, a Times spokesman, said he didn't know the cause of the problem, which hit the company at around noon EDT Friday. Employees, including the paper's reporters and editors, were instructed within an hour to turn off their PCs. Mr. Usnik said the publisher plans to publish a paper tomorrow, possibly using backup systems. A number of rogue computer programs have...