Recently had a user ask about VPN on Windows 8 not working, and then I realized he was using a Macbook with Bootcamp installed. He was getting error 442 Unable to enable virtual adapter.
After some quick searching around, I found that you could do the following:
First, you need to fix the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\CVirtA\DisplayName
It will be set to something like “@oem8.inf,%CVirtA_Desc%;Cisco Systems VPN Adapter for 64-bit Windows” – drop everything before “Cisco Systems” from that value.
Next, when using certs, you cannot use your certificate from the local user store. Rather, import the certificate to the local computer store and delete it from your user store. This should resolve error 403 Unable to contact the security gateway.