Like other Linux distributions, Fedora has the software repository scheme of things for software installation and updating. However, it could do with having the ability to remove unwanted repositories through a GUI but it doesn’t. What you need to do instead is switch to root in a terminal using the the command su -- and entering you root password before navigating to /etc/yum.repos.d/ to delete the troublesome [file name].repo file. Recently, I needed to do this after upgrading to Fedora 14 or Yum wouldn’t work from the command line, which is the way that I tend to update Fedora (yum -y update is command that I use and it automatically does all installations unattended until it is finished doing what’s needed). The offending repository, or “Software Source” as these things are called in the GUI, was belonging to Dropbox and even disabling it didn’t make Yum operate from the command like it should so it had to go. Maybe Dropbox haven’t caught up with the latest release of Fedora but that can be resolved another day.