"uninitialized constant Gem::Etc (NameError)" when starting server

I keep getting this when I try to start the server:

[Macintosh:rails/work/demo] jslicari% script/server /Library/Ruby/Site/1.8/rubygems.rb:723:in `set_paths': uninitialized constant Gem::Etc (NameError)   from /Library/Ruby/Site/1.8/rubygems.rb:719:in `each'   from /Library/Ruby/Site/1.8/rubygems.rb:719:in `set_paths'   from /Library/Ruby/Site/1.8/rubygems.rb:526:in `path'   from /Library/Ruby/Site/1.8/rubygems/source_index.rb:66:in `installed_spec_directories'   from /Library/Ruby/Site/1.8/rubygems/source_index.rb:56:in `from_installed_gems'   from /Library/Ruby/Site/1.8/rubygems.rb:736:in `source_index'   from /Library/Ruby/Site/1.8/rubygems.rb:140:in `activate'   from /Library/Ruby/Site/1.8/rubygems.rb:49:in `gem'   from ./script/../config/boot.rb:59:in `load_rails_gem'   from ./script/../config/boot.rb:53:in `load_initializer'   from ./script/../config/boot.rb:38:in `run'   from ./script/../config/boot.rb:11:in `boot!'   from ./script/../config/boot.rb:109   from script/server:2:in `require'   from script/server:2

I have made sure everything is up to date with "sudo gem update" and "sudo gem update --system"

Here are the versions I have:

[Macintosh:rails/work/demo] jslicari% gem -v 1.3.1 [Macintosh:rails/work/demo] jslicari% ruby -v ruby 1.8.1 (2003-12-25) [powerpc-darwin] [Macintosh:rails/work/demo] jslicari% rails -v Rails 2.2.2

Thanks

Your version of ruby may be too old. See http://rubyforge.org/tracker/index.php?func=detail&aid=22313&group_id=126&atid=575