i can’t get windows 2000 vpn feature to

I have a computer set up with windows 2000 Server. It has 2 NICs one for my internal 192.168.0.x network and for my cablemodem(dhcp). I am trying to configure RRAS on windows 2000 to run it as a VPN which is a direct option. I configured it and started the service, and my internet connection dropped, i can’t see the outside world and the outside world can’t see me, i can’t ping my ip from outside until i stop the rras service. PLEASE HELP!!!!!
Also this computer is running Internet Connection Sharing to share the cable modem across my internal network