Apparently the upgrade of GTK from version 2.xx to 3.xx didn’t quite go perfectly in the development of Fedora 15. There’s a package that needs to be installed, and for some reason, it isn’t. I think this package is needed so that PackageKit can automatically catch requests for fonts that you haven’t installed and offer to get them for you. You get an error from a lot of new programs:
Failed to load module "pk-gtk-module"
It’s easy to fix, and at some point they’ll probably fix one of the other packages to require it as a dependency, and the problem will go away when you install updates. But here’s how to do it manually. At the command line, become root and give the command:
yum install PackageKit-gtk3-module
That should install it for you and get rid of this error message. There’s a similar package for GTK 2.xx called PackageKit-gtk-module (no “3”) that affects some programs but it was already installed on my systems.