Mac: OS X Mavericks hasn't had the best launch in history, and one of the more common problems is downloads stalling midway. Wired offers the remedy for this and a few other Mavericks growing pains.
To fix a download that's stuck midway through and says "paused", just pop over to Launchpad, locate the app being downloaded, and hold the Option key until the apps jiggle. Then hit the "X" to delete the offending papp, then download it again.
It's not a great fix, but it's better than nothing. Head over to Wired for a handful of other workarounds, including fixes for Gmail problems, broken scroll bars in Chrome, and Mail forgetting your password.