Vibrating camera

Hi!
I have a Sony DSC-T20 digital camera that is about 2 years old. The camera has started vibrating sometimes when turned on and the photos come out fuzzy. When opening the camera (by pulling the front part down) it starts to vibrate quite noisily. Sometimes it settles down after a second or two and works as normal. Other times it continues to vibrate and the view is shaky and photos come out shaky too. It seems to be getting worse. The camera is totally unreliable because I know I only have a couple shots before it starts and won't stop.
Have you got any idea what could be causing this?
Thanks,
Lisa