I had this problem, and I found it on the internet.
In Window 8, when connect to a vpn server, window 8 gives your error, but why? The same configuration with Win 7 works extremely well.
To make Cisco AnyConnect Client work in Win8, you should make a small fix in Window’s registry:
Windows Registry Editor Version 5.00
"DisplayName"="Cisco AnyConnect VPN Virtual Miniport Adapter for Windows x64"