I'm trying to install the proprietary AMD drivers through Software Sources. I tick the box for fglrx-updates, and it says applying changes and fills 10% of a progress bar. It then sites there for hours (I left the computer unattended). Trying to get this process to finish, I found that the Ubuntu software center progress tab display a message reading: Applying Changes: Waiting for required medium What in the world does that mean and how can I get it to move on?