Ruby and rails wont work even they're already installed

mongskie@mongskie-os:~$ gem
/usr/bin/gem:4: undefined method `manage_gems’ for Gem:Module

mongskie@mongskie-os:~$ rails
/usr/lib/ruby/1.8/active_support/dependencies.rb:55: uninitialized
constant ActiveSupport::Dependencies::Mutex (NameError)
from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in
gem_original_require' from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:inrequire’
from /usr/lib/ruby/1.8/active_support.rb:56
from /usr/share/rails-ruby1.8/railties/bin/…/lib/rails_generator.rb:
28:in require' from /usr/share/rails-ruby1.8/railties/bin/../lib/rails_generator.rb: 28 from /usr/share/rails-ruby1.8/railties/bin/rails:14:inrequire’
from /usr/share/rails-ruby1.8/railties/bin/rails:14

I always get these messages. Why is this. Pls help me.

I can only advise you to use rvm (type this in Google ) and update your
and rails to newest version.
On 4 Jul 2011 12:39, “Mongskie” [email protected] wrote:

from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:36:in

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If you can’t update Rails or downgrade RubyGems, you need to require
‘thread’ before boot.rb runs, in three files: Rakefile, script/server,
config/environment.rb. It seems older versions of Rails relied on a
from RubyGems, giving us that delightful error message upon updating
RubyGems to a newer version, which does not require thread.rb by
More info: