Demand Dial Reconnect

I have set up a one way demand dial VPN PPP connection over a cable modem from a 2003 server to a SBS 2000 server with a fixed IP on the SBS2000 server.It appears to be working fine until a disconnect and then the only way I can get a reconnection is to delete the interface on the remote 2003 server and remake the interface. Any ideas what’s going on and how I can fix it?