Newbie with error

I just installed the following:

I am running on OSX 10.4. 10
I followed Hivelogic versions and installed
ruby 1.8.6 (2007-03-13 patchlevel 0) [powerpc-darwin8.10.0]
rails 1.2.3
mysql Server version: 5.0.41 MySQL Community Server (GPL)

I am getting this error when trying to run a very simple app.

dyld: NSLinkModule() error
dyld: Symbol not found: _rl_filename_completion_function
Referenced from:
/usr/local/lib/ruby/1.8/powerpc-darwin8.10.0/readline.bundle
Expected in: flat namespace

Trace/BPT trap

I think this is a OSX/Ruby bug.
Because I am a newbie, I need explicit help with the fix.