I have run across this issue when installing both the Cisco AnyConnect VPN client and the traditional Cisco VPN client. Once the client is installed and you attempt to establish the VPN connection you might get one of the following messages: “Unable to establish VPN” or “The VPN client driver encountered an error.”
The fix is you need to change the “Display Name” in the registry. Open the following registry key and take out the extra INF stuff at the front of the “Display Name” data. The different VPN clients use different Registry keys.