I am trying to get Rails to work on Windows 10. I am using Ruby 2.3.0, and Rails 4.2.6, and am temporarily using Nokogiri 1.6.3.
When I try running rails new d
rails new d
I had the same problem as you. On Windows you need to perform an additional step:
http://www.nokogiri.org/tutorials/installing_nokogiri.html