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
iOS 5 Looks to be the main Causes for the Three Fold Increase In Twitter Signups –
Twitter CEO Dick Costolo has recently said that Twitter sign ups through IOS devices have tripled since the launch of iOS 5 . Twitter is a big feature in IOS5 which was released last Wednesday. The integration makes it easier to tweet anyone in your Contacts who have a twitter handle to there name. The new features also make it a lot easier for users to tweet pictures and also websites. At this current stage Twitter is the first third party company to have been build is a IOS.