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
Apple Seed OS X Mountain Lion 10.8.1 To Developers
Apple has just released the first build of OS X Mountain Lion 10.8.1 to developers. OS X 10.8.1 comes in at 36.5MB and the beta’s build number is 12B13 and is now available on from the Mac Developers Center.
More information coming soon.
OS X Mountain Lion