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 Testing A6 Based iPad Mini For Faster Performance
A leak in iOS 7 beta 4 has proven the recent rumours that Apple is testing the next generation iPad mini which includes improvements to the device’s performance put not a retina display.
The reference to the new iPad mini can be found in a hidden file within the most recent beta of iOS 7. The file lists all iOS 7 supported device and the corresponding details about each device. The list includes three new models of the iPad mini including the “iPad 2,8,”,”iPad 2,9,” and the “iPad 2,10,”. The code names for theses models are the following, J75, J76 and J77.
The image below shows s5l8950x as the processor for the J75 model of the next generation iPad mini and as we already know from the iPhone 5 that this means it will include an A6 processor which will drastically improve the performance and speed of the the iPad mini.
Since Apple launched the iPad mini everybody has been wanting a retina display and with more competition coming from the Google Nexus 7 it seemed like Apple have no other choice but at the moment it seems like we won’t be seeing a retina display iPad mini any time soon. Included in the packages for retina devices you would normally expect to see linked “@2x” mode which allows developers to upload retina versions of their graphics but these are not visible with in the iPad mini (J75) package in iOS 7 beta 4.
This does not mean that Apple is not working on a retina version of the iPad mini as it is rumoured to be know as the J85 iPad but this is not referenced as of yet.