I'm new so I just can't figure out what's going on here. I was going through a tutorial to learn the ins and outs of Rails and then it just stopped working.

Here are the errors.
[rake --tasks] rake aborted!
Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes.
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/execjs-1.2.11/lib/execjs/runtimes.rb:47:in `autodetect'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/execjs-1.2.11/lib/execjs.rb:5:in `<module:ExecJS>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/execjs-1.2.11/lib/execjs.rb:4:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/coffee-rails-3.1.1/lib/coffee-rails.rb:1:in `require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/coffee-rails-3.1.1/lib/coffee-rails.rb:1:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `each'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `block in require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `each'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/bundler-1.0.21/lib/bundler.rb:122:in `require'
W:/RubymineProjects/blog/config/application.rb:7:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
W:/RubymineProjects/blog/Rakefile:5:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load_rakefile'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:501:in `raw_load_rakefile'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:82:in `block in load_rakefile'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:81:in `load_rakefile'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:65:in `block in run'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
W:/RailsInstaller/Ruby1.9.2/lib/ruby/gems/1.9.1/gems/rake-0.9.2.2/bin/rake:33:in `<top (required)>'
W:/RailsInstaller/Ruby1.9.2/bin/rake:19:in `load'
W:/RailsInstaller/Ruby1.9.2/bin/rake:19:in `<main>'
I tried "gem install execjs". No change. I tried reinstalling Ruby, then Rails. No change. What could I have possibly done? Is it really as fragile as it seems or did I just make a terrible mistake?