Have a network of six computers, Dell Diminsions, Windows XP,one computer does  the dialing to connect to the internet, 56k modem. After I disconnect from the Internet, the modem immediately dials out again. When I disconnect it stays that way until I redial. I disconnected the network and the problem stopped. I can not find out what program or computer is constantly dialing out to the Internet after shut down of # 1 computer. All automatic up-dates are off. Have Norton System works, SpyBot, and routinely run virus checks etc. Also I changed the modem twice. Same problem.

Any ideas what may be the problem.