yum on Fedora 12 showing an impossibly long estimated time

YUM estimated this afternoon that installing Xfce would take approximately 7 * (10 ^ 40) hours to download and install. According to my calculations, this means it'll be done in roughly…

809,589,041,095,890,410,958,904,109,589,041,095,890

…years, which as far as I know would be enough time to form at least a few million new universes. I'd better go put another pot of coffee on.