If it was working before, what changed?

Are there other users with your level of access to that machine?

What about ENV (environment variables)? check your ~/.bashrc , is there anything new in there for paths, libs etc? Check for symlinks in /usr/lib/perl* between directories

Edit: I forgot to mention I don't get these issues on the test machine.

• It may also be worth looking over your cpan config...

  It may be somewhere like '/usr/lib/perl5/5.8.8/CPAN/Config.pm' .. I think maybe older CPAN was using the ~/.cpan dir or something with config- not certain about that. The default config can be overridden with ~/.cpan/CPAN/MyConfig.pm (see below)

  Try # locate CPAN | grep -i config

  Here is one of mine (/usr/lib/perl5/5.8.8/CPAN/Config.pm), in case something really different stands out..

  
  # This is CPAN.pm's systemwide configuration file. This file provides
  # defaults for users, and the values can be changed in a per-user
  # configuration file. The user-config file is being looked for as
  # ~/.cpan/CPAN/MyConfig.pm.
  
  $CPAN::Config = {
    'auto_commit' => q[1],
    'build_cache' => q[10],
    'build_dir' => q[/root/.cpan/build],
    'cache_metadata' => q[1],
    'commandnumber_in_prompt' => q[1],
    'cpan_home' => q[/root/.cpan],
    'dontload_hash' => {  },
    'ftp' => q[/usr/bin/ftp],
    'ftp_passive' => q[1],
    'ftp_proxy' => q[],
    'getcwd' => q[cwd],
    'gpg' => q[/usr/bin/gpg],
    'gzip' => q[/usr/bin/gzip],
    'histfile' => q[/root/.cpan/histfile],
    'histsize' => q[500],
    'http_proxy' => q[],
    'inactivity_timeout' => q[0],
    'index_expire' => q[1],
    'inhibit_startup_message' => q[0],
    'keep_source_where' => q[/root/.cpan/sources],
    'make' => q[/usr/bin/make],
    'make_arg' => q[],
    'make_install_arg' => q[],
    'make_install_make_command' => q[/usr/bin/make],
    'makepl_arg' => q[],
    'mbuild_arg' => q[],
    'mbuild_install_arg' => q[],
    'mbuild_install_build_command' => q[./Build],
    'mbuildpl_arg' => q[],
    'ncftp' => q[/usr/bin/ncftpget],
    'ncftpget' => q[],
    'no_proxy' => q[],
    'pager' => q[/usr/bin/less],
    'prerequisites_policy' => q[follow],
    'scan_cache' => q[atstart],
    'shell' => q[/bin/bash],
    'show_upload_date' => q[0],
    'tar' => q[/bin/tar],
    'term_is_latin' => q[1],
    'term_ornaments' => q[1],
    'unzip' => q[/usr/bin/unzip],
    'urllist' => [q[ftp://cpan.pair.com/pub/CPAN/], q[ftp://carroll.cac.
  +psu.edu/pub/CPAN/]],
    'use_sqlite' => q[0],
    'wget' => q[/usr/bin/wget],
  };
  1;
  __END__
  [download]

  Also, I am assuming you are running as root.. look inside ~/.cpan/CPAN/MyConfig.pm, is that file there? Anything strange?

• And you did mention you looked inside ~/.bashrc and there's nothing freaky.

• Maybe also compare the test and production machines cpan configs (against each other).. and their env set variables ( with '# set' ).

• And maybe '# uname -a' on both machines, maybe check google for anything with cpan fails and that architecture.. google for = 'site:http://www.linuxquestions.org/ $architecture cpan failure' (there may be something)

(You probably already did all of this, I don't want to seem patronizing)

I have located the config and it is fairly different from the test machine. Nothing obvious jumps out. What is really clear however is that I am not even really sure what I want from the CPAN config. I mean in test at least at the moment I probably want to bang stuff in. So my action plan seems to be:
• Try installing a private 5.8 version of perl in test.
• Look at lower memory solutions like CPAN::SQLite.
• Learn treat CPAN as a friend and get to know it more intimately.
Maybe one day I will have a budget to throw at the problem, in the meantime thanks to everyone for their help.