Windows 2000 microsoft’s vpn problem

I’m using microsoft’s vpn to access my network remotely. The internet access is provided by a router cisco 2600. The vpn is configured in a Windows NT 4 server. I have no problem’s accessing and pinging the servers when connecting from windows 98, but if I use windows 2000 the connection is established, yet I cannot ping any of the servers within the remote LAN. Any ideas or suggestions?