To resolve this issue, remove the proxy server settings from the dial-up networking connections:
Click Start, and then click Internet Explorer to start Internet Explorer.
On the Tools menu, click Internet Options.
On the Connections tab, double-click the dial-up networking connection under Dial-up settings to display the Dial-up networking connection Settings dialog box.
Click to clear the Use a proxy server check box.
Repeat steps 3 and 4 for each dial-up networking connection that is listed.