If you have installed the Windows 8 Consumer Preview and use Cisco AnyConnect you may run in to a problem when attempting to connect. I got the error “The VPN client driver has encountered an error”.
First off I spotted a warning in the event log instructing the Cisco AnyConnect VPN Client must be reinstalled after upgrading Windows, which I completed and still found I could not connect.
After a bit more digging I noticed the VPN adapter, Cisco AnyConnect VPN Virtual Miniport Adapter for Windows x64, was not Enabled (usually disabled when not in use) when the connection was initiated. Looking in the Registry I could see the DisplayName string value did not match the name of the adapter, so updated as below.
Windows Registry Editor Version 5.00[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\vpnva]
"DisplayName"="Cisco AnyConnect VPN Virtual Miniport Adapter for Windows x64"
Restarting the Cisco AnyConnect VPN Client and clicking Connect now works.
If connecting from Internet Explorer 10 ( E.G. https://vpn.noak.es/office) you may need to set the web page to use Compatibility View to launch the client using ActiveX and connect.