Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Mac OS X Mountain Lion Launching July 25th ?
At WWDC 2012 Apple announced they would be launching Mac OS X Mountain Lion to the public in July but did not mention any specific dates. Today we have heard from a few a couple of Apple employees based in America who have mentioned that they have been asked to work overnight to launch OS X Mountain Lion.
Another factor which makes us believe it will launch on the 25th July is Apple has a earnings call scheduled for the 24th. This matches with the launch of OS X Lion which was launched on the 20th July again just a day after a Apple’s earnings call which was held last year on the 19th July.
From speaking to a few more over sea’s apple retail employees it sounds like a lot of stores have not been informed about the extended overnight shifts.