Create VPN connection results in Dial-up connection

This is a Windows Vista Ultimate desktop using which I created a VPN connection and made it 'Connect to a workplace' and selected 'Use my Internet Connection (VPN)’ option. As part of the setup I also enter the Internet address and assign a name to the connection. The connection is also showing up in Manage Network Connections but it says “Unavailable - device missing.”

When I check its properties, it says 'Modem Removed - Unavailable device ().” I don’t know what it means. Can anyone please tell me way of getting rid of this ? Thank you.

I had this problem once with my Vista and after struggling lot, finally I called up Microsoft Technical Support. After checking the system they realized that the problem is with Vista itself and hence they provided me 'grace call' that use to be free of charge. They said me that the problem was with operating system itself and I need to re-install it again. I did the same and created new VPN. Guess what problem solved. So you should try re-installing the OS, it may help.

I have the exact same problem with a Windows 7 Ultimate installation on a laptop. There was nothing new installed, it just started throwing the errors one day...

Here is what I have found so far, maybe someone else will have a lightbulb moment... I will start backwards:

It seems VPN connections fail with a 797 error
If I open the properties of the VPN connection I see a "Modem Removed- Unavailable device ()" in the Connect using: box. The FQDN/IP of the VPN server is in the Phone number: box for me as well.
At one point I was able to delete the connection and re-create it and the new, working connection was stable for a few hours, through a couple of reboots. Then it crapped out. Now I am not even able to do the "delete/recreate" thing anymore.

One other thing I noticed (and this may be key) - in Device Manager, if I choose "View --> Show hidden devices", under "Non-Plug and PLay Drivers" I have NDProxy with a yellow exclamation sign. NDProxy, according to MS is "a system-provided driver that interfaces NDISWAN and CoNDIS WAN drivers (WAN miniport drivers, call managers, and miniport call managers) to the TAPI services" - see http://msdn.microsoft.com/en-us/library/aa938462.aspx

It has been linked to quite a few slow boot, BSOD and other issues with Vista. Nothing (so far) with W7.

So.... ANY ideas? I am a few frustrating hours away from setting up something else for VPN and just chucking RRAS... :(

Interesting observation/progress (not sure if it is a solution, yet)...

As I stated before, the NDProxy Non-Plug and Play Driver in Device Manager shows as "This device is not started... because some if its drivers are missing..." or something to that effect (I can't tell you the exact text now, because I _THINK_ I fixed it, at least temporarily).

If you go to the second tab (Driver) and look at the Current Status section, it says it is Stopped. You have the option to start it. Do that and then reboot. After the reboot the device is no longer with an exclamation icon (i.e. it started OK) and it shows Started in the Current Status.

If you try to create a new VPN connection, it works fine - connects and everything... :) It seems to stay after a reboot too.

Now the thing is... It sort of did that before, although back then I simply deleted the old VPN connection (thinking it got corrupt somehow) and re-created it - no device starting, no reboots. So let's see if this sticks... Stand by...