I have read all the questions for the same problems and I have tried everything but nothing is working for me when I try to add android platform for cordova.
This link http://spring.io/guides/gs/android/ + running cmd as an administrator solved that issue for me.
This confirms Michael Brooks' assumption that this issue has to do with permissions settings on the Windows OS. https://github.com/phonegap/phonegap-cli/issues/77