Has anyone else had problems with any of the Sony Alpha models? Last year my 3 year old A100 packed up and I ended up replacing in December with the A550. This developed what appears to be the same fault at the weekend - shutter release becomes hard and wont focus and I am unable to use any of the buttons to manually change any settings. When I had my A100 checked out I was told the 'motherboard' (can't remember what the guy called it) had 'gone' and this appears to be the same symptoms. Sony are definitely not the most helpful company to deal with when a problem, but I am a tad concerned that there may be an inherent problem