Internet service for many in China ground to a halt for eight hours yesterday as a result of what may have been a mistake made by Chinese censors. Many of China's half a billion Internet users were unable to get to .com, .org, or .net addresses because Chinese Internet traffic was being routed to servers operated by a shadowy company based in Cheyenne, Wyoming. A cyberattack was initially suspected, but American experts, noting that the Wyoming servers are owned by a company that helps Internet users cover their tracks, surmised that Chinese authorities trying to block access to the servers may have inadvertently directed traffic to them instead.