Time Warner ( TWX) joined the host of big U.S. companies warning that personal information has been lost on its watch.The New York media giant said Monday that a container of its computer back-up tapes was lost by an unidentified outside data storage firm during shipment to one of that firm's storage facilities. The missing tapes contained data including personal information on current and former Time Warner employees. The tapes didn't include personal data on Time Warner customers, the company said. The company said the Secret Service is investigating and that so far there's no evidence that the tapes or their contents have been accessed or misused. The news comes in the wake of a rash of incidents in which personal information was stolen from or mistakenly divulged by big companies including Reed Elsevier ( RUK) unit LexisNexis and Polo Ralph Lauren ( RL). Time Warner rose 6 cents to $16.87 Monday.