I'm running 10.7.5 on a MacBook Pro 2010 with all the latest updates. I have about 30 GB of free space which should be more than enough. The faded out icon in Launchpad says downloading but it has been stuck at the beginning for almost an hour. I've tried pausing and unpausing but it didn't help. If I go to purchases in the Mac App Store, Mavericks has a Download button, and if I click it, it becomes white and reverts back to grey after a few seconds. If I got to the Mavericks page in the Mac App Store, the download button quickly switches from "Downloading" to "Download" and back to "Downloading" and then stays there. Clicking it doesn't do anything. Has anyone experienced this? Can anyone help me? Thanks!