Network Sharing

I setup Internet sharing on a Win2000 File server. the problem is it keeps dialing out without anyone trying to surf the web or retrieve e-mail. I have the connection set to hang up after 20 minutes of no use and the redial set for 1 minute. The workstations are Win2000. How can I stop this redial, and only dial on demand. Which it the way I have it set up as.