IO::Socket is a core module that comes with Perl. If you are missing this module, your installation of Perl was botched or broken. I'd check to see if you aren't doing anything screwey with your Perl environment variables, switches, or munging @INC somehow. Failing that, perhaps you need to reinstall Perl?
I've tried reloading the IO module and I still had the same problem. Somehow DBD::Informix dinks with it. I'll probably have to reinstall perl, add the libnet and then reinstall DBI/DBD. Thanks for your help.
How did you "reload" the IO modules? They are bundled with Perl, so you couldn't have reloaded them without re-installing Perl...??? Or were they bundled separately in earlier versions of Perl and this is what you are using? The only IO::Socket-related module that seem to be available on its own is IO::Socket::Unix, but I don't think this has anything to do with what you're doing.