Problem with MX5000 keyboard

I've had this keyboard for over a year. After a few months it started malfunctioning. When I press a key, it will continuously type the same letter/number/symbol over and over again. The only way to make it stop is to turn it off and reconnect it, but half the time THAT doesn't work either. This has resulted in the loss of a lot of work, because the backspace button is the worst culprit. It erases everything I've typed, and continues to backspace, so i can't type anything without it getting messed up. I've been using the on-screen keyboard for everything, which obviously takes a long time. I've tried everything I can think of, the batteries are new, and no matter what it's still going crazy. Is it fixable, or should i just chuck it out the window and buy a new one?