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
Exspect Compact Clock ,Radio, Speaker and Dock Review –
The new COMPACT Radio Alarm Dock was sent to us by MobileFun for review. This product was launched back in 2010 and is still selling strong today. The Exspect compact is finished in a unique black rubberized paint, which means it will fit in any environment .The dock provides facility to recharge both iPod and iPhone ( Which it does extremely fast) . A Great extra feature to the product is that it is possible for you to set two separate alarm clocks which could use the alarm for you and your partner or set one alarm for week days and one for weekends. The alarm offers you the option to choose what you want your walk up call. You can choose from the radio , iPod or a plain buzzer. The sound quality on this small device is excellent for the price and does improve a lot when on a flat and solid surface. The blue back lite LED on the front makes it easy to see the clock in a dark room.
Buy this product here :
Mobilefun.co.uk does some great iPhone 4 accessories
More information in the video below