If you install the Cisco VPN client in a Windows 7 OS some times you may see an error saying that;
Reason 442: Failed to enable Virtual Adapter
In such a scenario try to do following thing.
First go to services or type services on the search and find the "Internet Connection Sharing (ICS)" service. Stop that service and change the service start-up option to manual. Then try to restart the "Cisco Systems, Inc. VPN Service" service.
Now try to use the VPN client.