You have not quoted the previous message so I am not sure if you saw
my latest post. The problem appears to be that you have a random
assortment of rails gems. All of actionmailer, actionpack,
activerecord, activeresource, activesupport and rails itself should be
available for the version that you specify in environment.rb (2.3.5 in
the case of your app). It is nothing to do with which version of
ubuntu you are on, it is to do with which gems have been installed.
As I said I would suggest you install rvm then you can install the
appropriate gems for the app under rvm and ignore what is currently
installed. I also note that you have ruby 1.9.1, I would suggest
1.8.7 for rails 2.3.