Hartl Chapter 3 gemfile bundle install issue
===

I am new to rails and am working through the Hartl online tutorial. I updated my gemfile as the book suggests to 

source 'https://rubygems.org'

gem 'rails', '3.2.6'

group :development, :test do
  gem 'sqlite3', '1.3.5'
  gem 'rspec-rails', '2.10.0'
end

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '3.2.4'
  gem 'coffee-rails', '3.2.2'
  gem 'uglifier', '1.2.3'
end

gem 'jquery-rails', '2.0.0'

group :test do
  gem 'capybara', '1.1.2'
end

group :production do
  gem 'pg', '0.12.2'
end

then went to my command prompt and entered: bundle install --without production

I keep getting the same error message stating: 
Errno::EACCES: Permission denied - C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/ffi-1.0.11/ext/ffi_c/libffi/configure
An error occured while installing ffi <1.0.11>, and the Bundler cannot continue.
Make sure that 'gem install ffi -v '1.0.11' succeeds before bundling.

I tried entering: gem install ffi
and it successfully installs the gem but when I rerun the bundle install command I get the same error message.

Any suggestions?