quoted from
Inability to browse often means the client can't resolve NetBIOS names.
1. If this is a workgroup network, enable NetBIOS over TCP/IP on the server and clients.
2. If this is domain network and the WINS server is on the same computer as the PPTP/VPN server, move the WINS server to a different computer.
3. Add the NetBEUI protocol for your PPTP tunnel instead of, or in addition to, TCP/IP.
4. By default, most routers and firewalls prevent the transmission of NetBIOS names unless you enable UDP ports 137 and 138 and TCP port 139. Try to enable UDP ports 137 and 138 and TCP port 139 across all routers and firewalls between the PPTP/VPN client and PPTP/VPN server.
5. Make sure the client has correct DNS, WINS and Master Browser settings.
6. Make sure the default gateway points to the remote network rather than to the ISP.
7. Some ISP might block ports required for NetBIOS name broadcasts.
8. If WINS address is not distributed upon connection to VPN, LMHOSTS should be configured to enable Domain to be located.
9. If you try these techniques and the client still can't browse, try to use UNC to connect to the remote resources by ip, for example, use the net use h: \\serverip\sharename command.
Robert Lin, MS-MVP, MCSE & CNE
Windows, Network, Internet, VPN, Routing and How to at