I have a similar problem like mentioned in this question:
Unable to create the virtual machine
But, my problem is a bit different in the error description:
It's already answered, but something easier worked for me (and without uninstalling VirtualBox):
"Go into Hyper V. Go into the Virtual Switch Manager. Create a virtual switch called 'Windows Phone Emulator Internal Switch'. Make it's connection type Internal. Now launch the emulator. It should work."
I had to reboot the machine before running the emulator, but now everything's working fine: VS2012, Xde and VirtualBox.
Credits go to TheGeekNextDoor.
It seems that Xde is currently not compatible with Cisco VPN Client v5.x; with the VPN client installed, you indeed get this error. Uninstalling Cisco VPN Client resolves this.
I was able to fix this by removing VMWare Player and Virtual Box, and then performing a Repair install of the Windows Phone 8 SDK (Control Panel-> Uninstall -> Windows Phone 8 SDK -> Change -> Repair
This what helped me to solve the same issue: http://mobileworld.appamundi.com/blogs/petevickers/archive/2012/11/01/troubleshooting-windows-phone-8-emulator-problems.aspx
And no need to uninstall virtualbox even have it running at the same time
Hope this will help to someone
Had the same error message. After removing VirtualBox, everything works fine
I had some issues getting this going. In the end, by randomly disabling and enabling my network adapters, I was able to get the virtual switch working even for an external adapter.