Remove settings from network cards no longer installed
Today I had a problem with a virtual guest machine (Windows server 2003) on a Hyper-V host. Now that I have found a solution on my problem I thought it would be nice to share it with your guys. I was getting this error after have made some change with my virtual NIC adapters.
The error I was facing, when I was making changes to the only NIC there was installed, was this one:
The IP address XXX.XXX.XXX.XXX you have entered for this network adapter is already assigned to another adapter Name of adapter. Name of adapter is hidden from the network and Dial-up Connections folder because it is not physically in the computer or is a legacy adapter that is not working. If the same address is assigned to both adapters and they become active, only one of them will use this address. This may result in incorrect system configuration. Do you want to enter a different IP address for this adapter in the list of IP addresses in the advanced dialog box?
The problem was that I had an old “ghost” NIC with some settings applied to it. The NIC was no longer installed so I was not able to remove or change the settings the normal way. First I tried to find the information in the registry, but there were a lot of entries and it didn’t seem to work. Then I did what I always do in those situations. I turned to doctor Google for a quick fix 
Doctor Google had a solution for me and here it comes:
1. Open a command prompt and enter the commands above.
2. From the view menu select: Show hidden devices
3. Select the NIC that are removed from the system and right click and chose “Uninstall”
The NIC that are grayed out are no longer in the system
After following the above steps I was able to change the IP settings on my NIC without any warning.
You can make this permanent by throwing it in a environment variable.
If you have the feeling X device is locked or messing about with registry and you really want it dead try Device Remover http://www.pro-it-education.de/software/deviceremover/ Don’t let website fool you. Check screenshots http://cid-13a411233fbf2d4d.photos.live.com/browse.aspx/Device%20Remover%20Screenshots if possible to fix it can fix it but program will not win any popularity contests. Very technical and does much more than devices.
Hope the link below is helpful:-
http://winplat.net/post/2010/12/20/How-to-remove-Phantom-Network-adapter.aspx
Thanks sushant, that worked great. We’re converting a bunch of physical machines to virtual and this is a quick and easy way to get rid of the warning messages when setting the IP address.