I'm having a problem when I try to install any apps from the Mac App Store. Once the app is purchased it appears on the Launchpad with a download then an installation progress bar. This is normal. However, when the installation progress bar completes, the app immediately disappears off of the Launchpad. I tried to reset my Launchpad thinking it would fix the problem, but now my Launchpad is empty and I can't add any apps to it (even tried dragging and dropping new items to it from my applications folder). Now that my Launchpad is broken; I don't think the problem installing Apps is even related to Launchpad because the apps are not appearing in my Applications folder either after installation. Anyone have any ideas I could try?