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’s OS X Mavericks To Be Released At The End Of October
According to a report published today Apple is planning on releasing Mac OS X Mavericks at the end of October to the public.
Earlier reports suggested that Apple would release both iOS 7 and OS X Mavericks at the September 10th keynote but that seems to have changed with Apple putting all of its focus on delivering iOS 7 to the public as smoothly as possible.
Now it seems the plan is to release iOS 7 around the 18th September within days of the release of the iPhone 5C and iPhone 5S then later in October release iOS 7 for iPad and then OS X Mavericks around the end of next month.
Apple maybe holding of on the Mavericks release to launch it along side their new Macs which are expected to be released this fall.