Depois de atualizar as gemas, eu tenho o seguinte:

/home/megas/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/psych.rb:148:in `parse': couldn't parse YAML at line 182 column 9 (Psych::SyntaxError)
    from /home/megas/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/psych.rb:148:in `parse_stream'
    from /home/megas/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/psych.rb:119:in `parse'
    from /home/megas/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/psych.rb:106:in `load'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/RedCloth-4.2.3/lib/redcloth/formatters/latex.rb:6:in `<module:LATEX>'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/RedCloth-4.2.3/lib/redcloth/formatters/latex.rb:3:in `<top (required)>'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/RedCloth-4.2.3/lib/redcloth.rb:21:in `require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/RedCloth-4.2.3/lib/redcloth.rb:21:in `<top (required)>'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/RedCloth-4.2.3/lib/case_sensitive_require/RedCloth.rb:6:in `require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/RedCloth-4.2.3/lib/case_sensitive_require/RedCloth.rb:6:in `<top (required)>'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler/runtime.rb:68:in `require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler/runtime.rb:66:in `each'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler/runtime.rb:66:in `block in require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler/runtime.rb:55:in `each'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler/runtime.rb:55:in `require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/bundler-1.0.10/lib/bundler.rb:120:in `require'
    from /home/megas/Work/railscasts/config/application.rb:10:in `<top (required)>'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/railties-3.0.3/lib/rails/commands.rb:28:in `require'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/railties-3.0.3/lib/rails/commands.rb:28:in `block in <top (required)>'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/railties-3.0.3/lib/rails/commands.rb:27:in `tap'
    from /home/megas/.rvm/gems/ruby-1.9.2-p136/gems/railties-3.0.3/lib/rails/commands.rb:27:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

Trilhos ruby-1.9.2-p136 3.0.3

Tentei reinstalar o gem RedCloth, não ajudou, o sistema quer usar apenas a versão 4.2.3

Alguma idéia de como consertar isso? obrigado