LAPTOP SHUTS DOWN WHEN CONNECTED WITH LAN CAB

I have Toshiba Satellite A200-1MD, it does not shuts down when connected to LAN through DSL cable. It keeps restarting everytime until I remove the cable and shut it down. When using wireless connection through a router, there is no problem. Can anyone advise me about this problem and suggest a solution? It will be a great help... Harik God bless...