If you install an ISDN card after installing PPTP, the ISDN installation procedure might overwrite some of the files from your Dial-Up Networking upgrade. If this happens, you will no longer be able to use PPTP. You will need to remove all Dial-Up Networking components and reinstall your Dial-Up Networking upgrade.
To remove Dial-Up Networking
1. In Control Panel, click Add/Remove Programs.
2. Remove all Dial-Up Networking components.
3. Restart your computer.
To reinstall the Dial-Up Networking upgrade, follow the procedures outlined in “Installing PPTP on a Windows 95-based Client” in the chapter “Installing, Configuring, and Using PPTP with Microsoft Clients and Servers.”
Caution Never remove PPTP components using Network in Control Panel.