The 'fn' and 'menu' buttons plus control wheel aren't working properly

Just yesterday, when I press the 'fn' button, the selection bar jumps randomly around on the screen and even changes tabs at the top without me touching anything on the camera. Same thing happens when I press the 'menu' button. When I get a steady screen, I try to use the control wheel to move around in the menu but it sends the selection bar into hyper-drive. Sometimes, the menu will disappear and reappear every 1 or 2 seconds. My son used a small vacuum cleaner around each button in case there was something in there disrupting the contacts. Did not help. Has anyone else had this problem with ANY kind of camera and does taking the back off and using compressed air or a vacuum on the back side of the buttons help? Also, for the last month or so, the battery drains overnight if left in the camera even though the camera is turned off. I must remember to remove the battery after I've finished taking photos for the day. I'm talking about brand new Sony batteries.