Disconnected Mapped Drive & Network 3rd POST!!!!!

How come every time I load the incoming connection for
the VPN, I no longer can use my mapped drive or anything
else from the VPN host? In fact the entire network is
gone, I cant see any other system from the VPN hosts
system. And no clients can access the VPN Host system.
Now, how can VPN do anything for you if only the VPN or a
Client but NEVER BOTH can connect to the VPN host system?
I have a client/server app on the server and I want to
connect to it via the VPN. Well, I can, as long as nobody
on the other 150 systems in the office wants to work. As
soon as I delete the incomming connection from the
server, magically all the clients on the LAN can now use
the server again. Now, this is the THIRD POST and still
no repsonses yet.

Please, this is really agrivating.