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
OS X 10.9 To Bring Improvements To Finder & Multitasking
Apples code name for the upcoming OS X 10.9 release is “Cabernet” and 9to5Mac has learned that the new release will bring improvements to finder, multiple monitor support as well as taking some core features from iOS.
It is currently understood that it will not be a major overhaul of the whole operating system and it will still look, feel and function the same as it always does.
Some interesting enhancements to the new operating system include upgrades to the finder application and also a new version of Safari web-browser with re-designed back end for improved page loading and efficiency.
Another important power user feature coming in OS X 10.9 is the ability to keep a different space or full-screen application open at the same time.
According to 9to5Mac’s sources, the user interface will be changing slightly but there will be no overall major changes and it is still very much unclear whether we will see Siri integrated into this version.
Apple has reportedly been testing new multi-tasking systems similar to that of the app switching on the iPhone.
Apple will also likely announce Xcode 5.0 later this year. Apple’s new version of its developer app suite is said to be redesigned and include improved application testing tools.
Apple’s last two operating systems shipped in the summer, which suggests it is likely that 10.9 will also see a summer release. OS X 10.9 was originally scheduled to be previewed earlier this year, but Apple decided to introduce the operating system alongside iOS 7 at the upcoming Worldwide Developers Conference
We will have more information on this software release as it develops and you can follow us on twitter and Facebook for the latest breaking news and updates.
OS X Mountain Lion