I have this camera, bought this about 2 years back and it was great, good pictures & night shots, all indoors and outdoors but for about 4-5 months now all the pictures with flash are coming too dark, night shots are all dark and anything without flash comes distorted, I am not getting any great pictures from this anymore, and if there is any moving object (even the leaf) the whole picture comes shaky/shadowy. What could have gone wrong?

Also when I switch camera ON the flash is always turned on (in Auto mode) and I have to manually switch it off, so if I give this camera to anyone to take pictures they take all in flash mode if they are not familiar. Is there a way to have the flash off by default?