Again this is another note to myself, however it may be useful to others.
Yesterday I was attempting to run a Ruby script to check for ASP .Net Padding Oracle problems on a site and I got the following issue.
undefined method `lines’ for #<String:0x240d448>
I had looked at the Ruby Source code and all looked ok however there was still the issue when running the script.
It turns out that in Ruby Versions prior to Ruby 1.8.7 String doesn’t have a lines method and hence the error received. I was running Ruby 1.8.5
So the fix was a simple upgrade to the latest version of Ruby and then to run the script again and voilla the error is no more an issue.
Hope the above tip helps, if your receiving the same error.