SONY CYBERSHOT DSC W12 MALFUNCTION

Hi there, i think i have a mechanical problem with my camera. I have had the camera for 2 and a half years, and noticed the problem over the last 3 months, getting progressively worse. while having the camera switched on and on picture taking 'green icon' mode, you see the menu on screen flick automatically between modes. i have changed batteries but problem still there. Also, when about to take a picture, as i press button, the screen goes blank and you hear some whirring of the lens. you have to click the power button a number of times before it allows me to switch off or take a picture. Now the problem is more apparent and i couldn't switch it off to collapse the lens. is this problem common? how much could it be to repair the camera as it would be a shame to chuck it.

please help!!