On March 4, 2002, the control room operator’s LAN computer was restarted with a changed IP address.  The IP address duplicated the address assigned to an analyzer computer used for continuous emissions monitoring.  The analyzer computer locked-up as a result of the network error message due to duplicate IP addresses. 

At the time of the incident the analyzer computer was not isolated from the plant network by a firewall.  While the individual responsible for changing the IP address was not identified officially, it was reported that the address was changed to enable Internet access on the control room operators PC to play games.

The loss of signal from the analyzer computer forced a plant shutdown until the network communication problem was resolved 2 hours later.