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 Release iOS 6.1.2 To The Public
Apple has just released iOS 6.1.2 to the public for iPhone , iPad and iPod Touch. The update fixes the Exchange bug which was in iOS 6.1, improves battery life and also better network performance.
The update weighs in at 107mb and can be downloaded OTA and comes with the build number 10B146