I removed ActivePerl and reinstalled it.

It's not a matter of a broken Perl installation, so reinstalling won't help here. The problem is that you're using a compiler which that particular ActivePerl build doesn't play nicely with.

The file denoted by 'which cc' is a symlink pointing to the gcc executable; shouldn't that mean perl would use gcc to compile, if it was trying to use cc?

Yes, it does call gcc, but that's exactly the problem, because gcc and Sun's cc are sufficiently incompatible for things to work...

I installed Crypt::CBC with no problem.

The reason this did work is that Crypt::CBC is a pure Perl module. In other words, you don't need a compiler to install it.

According to this Blowfish shouldn't have any prereqs besides Crypt::CBC.

Presumably that's right. However, Crypt::Blowfish itself comprises architecture specific C/XS code, which means you need a working compiler installation to be able to build/install it.

I'm sorry, but unless someone comes up with a novel suggestion, I'm afraid there's not much else you can try, in addition to what I already did mention...