Local Area Network goes down after connectin to VPN

One of my clients use an app to dial to the net then
connect via another app to a VPN server. If i connect to
the net with the 1 app, the local network is still
accessible. When i connect to the VPN server the local
area network stops on the pc. You cannot browse
nieghbourhood or open outlook to the exchange server.

I have compared configs with another pc that does the
same but no luck. They are identical in every way from
network nieghbourhood to the app settings.

Any assistance would be greatly appreciated.
Ryan