I just had a horrorshow with my 505. The sounds have chamged!! Overnight, somehow, the sounds in the patterns (including presets) have changed. Where once was a Rise pad for instance is now a tom menu. What the..? I've backed up my user patterns (smart media card) and reset the factory presets then reloaded my user patterns. Everything is fine then all of a sudden boom, the sounds changed. What's wrong? Does it need a battery? Is the chip defective? Can you imagine if I was in the middle of a gig. Please help, I am desperate.