Hi guys, I downloaded OS X Mountain Lion to upgrade my previous OS X 10.6.8 version. It downloaded over night, and I checked to see if it completed and the full 4.3 gb or so downloaded completely. However when I opened the installer, after a couple of minutes of installing a message came up that said the application can't be verified. It may have been corrupted or tampered with during downloading. Please can someone help me with this, I tried restarting the computer but I don't know what else to do?