The timing of the outage was critical for Time Warner, which is working to win FCC approval of a $45 billion proposed merger with Comcast Corp., the nation's largest cable provider. Market experts say customers are frustrated by the frequency and handling of previously disclosed service disruptions. The company said it was investigating the cause of the disruption, which occurred as technicians conducted routine network maintenance on its Internet backbone. "We believe it to be human error that occurred during a routine overnight maintenance window," Amirshahi said. New York Gov. Andrew Cuomo ordered the state's Department of Public Service to investigate the disruption as it reviews the company's planned merger with Comcast. "Dependable Internet service is a vital link in our daily lives, and telecommunications companies have a responsibility to deliver reliable service to their customers," Cuomo said in a statement.