rails plugin error

Can someone explain what is happening in the stack trace?

[bryan@amac envoy]$ ss
=> Booting Mongrel (use 'script/server webrick' to force WEBrick)
=> Rails application started on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
** Starting Mongrel listening at 0.0.0.0:3000
** Starting Rails with development environment...
Exiting
./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:416:in `remove_const': cannot remove Object::ClassMethods (NameError)
         from ./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:416:in `remove_constant'
         from ./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:363:in `new_constants_in'
         from ./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:363:in `new_constants_in'
         from ./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:489:in `require'
         from /opt/local/lib/ruby/gems/1.8/gems/mongrel-0.3.14/lib/mongrel/rails.rb:161:in `rails'
         from /opt/local/lib/ruby/gems/1.8/gems/mongrel-0.3.14/bin/mongrel_rails:110:in `cloaker_'
         from /opt/local/lib/ruby/gems/1.8/gems/mongrel-0.3.14/lib/mongrel/configurator.rb:138:in `listener'
         from /opt/local/lib/ruby/gems/1.8/gems/mongrel-0.3.14/bin/mongrel_rails:96:in `cloaker_'
          ... 10 levels...
         from ./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:337:in `new_constants_in'
         from ./script/../config/../vendor/rails/activesupport/lib/active_support/dependencies.rb:489:in `require'
         from ./script/../config/../vendor/rails/railties/lib/commands/server.rb:39
         from script/server:3