In the OP, you said the paths were in @INC. But since PERL5LIB simply adds to @INC, it appears that you were mistaken, and that was I operating under incorrect information.

So, ignore that bit about permissions. What you have is a very broken installation of Perl. You shouldn't have to tell Perl where to find Config. You should reinstall it; you shouldn't be applying hacks like using PERL5LIB.