KDX client gets disconnected after reinstalling OS

After reinstalling OS X, I was having trouble with a KDX client being disconnected every 15 minutes or so, despite the fact that “regularly ping servers” was on. It turned out that in reinstalling, the energy saver settings had been set back to the factory defaults, and the CPU and hard disk were both sleeping after 15 minutes of non-activity. Setting the sleep settings for those two items to “never” fixed the problem.