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 7 Beta 6
Apple has just unexpectedly released iOS 7 beta 6 to developers for iPhone, iPad and iPod Touch.
This update is just a quick fix related to issues with iTunes in the cloud which explains the small size of 13.5mb , this means that it is very likely that Apple have not made any noticeable changes but if you do find anything when browsing through beta 6 then let us know Tips@MacReviews.com