Whenever I run something with Ruby on my server, I get the following error:
/usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/yaml.rb:56:in `
I had this same libyaml issue with CentOS 6.2
Doing...
rvm pkg install libyaml rvm reinstall 1.9.3 --with-libyaml-dir=/usr/local/rvm/usr
Fixed it for me.
(thanks to @Eugene)