I'm completely at a loss as to how to deal with this.

Upgrade your Perl, either by compiling from source or installing a more up-to-date RPM. I don't know how or why but Redhat managed to produce several builds of Perl 5.8.x without support for weak-refs. I've seen this problem several times in reports about Config::ApacheFormat, which uses Scalar::Util's weaken(), and each time it's been a bad Redhat Perl to blame.

-sam