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 Annouce "Tech Talk World Tour 2011" For Developers Working With IOS5 –
We have seen Apple hold “Tech Talk” before and now they have just annouced they will be holding another one this year which is going to cover IOS5. Tech Talk will be visiting 9 Major cities around the world Including Seattle, New York, Austin, Texas, Berlin, London, Rome, Beijing, Seoul, and Sao Paulo. The event is free to attend for developers.