First, I would upgrade your system Perl through your package manager if at all possible. Then I would download the latest CPAN module and try to install it manually, then blow away /root/.cpan and reinstall. If that all doesn't work, then it seems to be one weird misconfiguration. You may have to take more drastic actions such as manually removing all modules installed after the system Perl was installed.
Other questions: Since you are using SLES, don't you have commercial support? Have any Perl modules been installed by your package manager? How is Perl used on your system (e.g., cron or other system scripts, individual users only, number of Perl users)? How many users do you support?
Update: I found that other folks using SLES 11 are having Perl update problems. If you need the Perl modules just for yourself, you should look at Perlbrew. You can also share the environment with others.