回复：Please help: 电脑一接 LAN， 其他运行程序的启动就慢下来.

It sounds like you are infected by the either virus or spyware. On command promp, type "netstat", you should see all the connection from your computer to other site or machines. if you find any connection should not be there, you are hit by the virus or spyware. if this is the case, check my post at http://web.wenxuecity.com/BBSView.php?SubID=computer_best&MsgID=360

get your antivirus and anti-spyware installed.

good luck