VPN and network shares (again)

> I know that there were already threads with this theme but all the
> suggestions and hints I found don't resolve our problems.
>
> I try to describe it as simple and clear as possible:
>
> Notebook
> - Windows Vista (Ultimate edition RTM, latest patches)
> - Domain member of blabla.local
> - using Outlook and network shares
> - integrated Windows PPTP-VPN-client (DNS, WINS and domain-suffix correctly
> set)
>
> Server
> - Windows Small Business Server 2003 R2 (latest patches)
> - Domain controller for blabla.local
>
> Firewall
> - Windows Server 2003 with ISA Server 2006
> - PPTP-VPN (works perfectly with all clients except Vista)
> - No domain member
>
> Situation 1: Notebook connected to company LAN
> Everythings works perfect. The network shares can be accessed and
> synchronisation (offline folders) works fine.
>
> Situation 2: Notebook connected via VPN
> Outlook works fine, but shares could not be accessed. Neither with explorer
> (\\server\share) nor with "net use" nor with browsing in the network
> neighbourhood. BTW, RDP works fine aswell.
>
> Among other things, I checked the following:
> - Disabling RPC-filter on the ISA Server
> - Upgrading the public net from where I started VPN to a private net
> (otherwise you cannot browse network neighbourhood at all)
> - Checked that netbios over tcp/ip is enabled on the server
> - Only IP4 enabled on Vista
> - Disabling firewalls on the SBS and on Vista
>
> Either I am too simpleminded to understand or the new network center in
> Vista is not really sophisticated. In my opinion it is stupid that I have to
> classify the public net as private to browse the network though I am
> connected via VPN with my domain network. Vista actually identifies my VPN as
> the domain network.
>
> BTW, we also encounter the same problems when we try to access foreign
> domains. The connection works fine. A remote XP client can even use a share
> on the Vista maschine but not the other way around.
>
> Thank you for any suggestions.
>
> Pepe