Ask HN: Error loading RubyGems plugin

So I have been trying to remove and reinstall RoR. Reason for that is, something bothered me the first time I installed it last week but I was just trying to learn it and wanted to remove it as soon as I got the book; Railsspace.

And now I am stuck with this:

$ gem install bundler Error loading RubyGems plugin "/Library/Ruby/Gems/1.8/gems/open_gem-1.4.2/lib/rubygems_plugin.rb": Could not find launchy (~> 0.3.5) amongst [abstract-1.0.0, actionmailer-3.0.10, actionpack-3.0.10, activemodel-3.0.10, activerecord-3.0.10, activeresource-3.0.10, activesupport-3.0.10, addressable-2.2.6, arel-2.2.1, builder-3.0.0, bundler-1.0.18, capistrano-2.8.0, capistrano-ext-1.2.1, colored-1.2, configuration-1.3.1, erubis-2.7.0, git_remote_branch-0.3.0, heroku-2.5.2, highline-1.6.2, i18n-0.6.0, launchy-2.0.5, mail-2.3.0, mime-types-1.16, mysql-2.8.1, net-scp-1.0.4, net-sftp-2.0.5, net-ssh-2.2.1, net-ssh-gateway-1.1.0, open_gem-1.4.2, polyglot-0.3.2, powder-0.1.6, rack-1.3.2, rack-mount-0.8.2, rack-test-0.6.1, railties-3.0.10, rake-0.9.2, rdoc-3.9.4, rest-client-1.6.7, rubygems-update-1.8.10, sqlite3-1.3.4, term-ansicolor-1.0.6, thor-0.14.6, treetop-1.4.10, tzinfo-0.3.29] (Gem::LoadError) ERROR: While executing gem ... (Gem::FilePermissionError) You don't have write permissions into the /Library/Ruby/Gems/1.8 directory.

How to solve this? Been googling and figuring it out for the last 4 hours!