What is your PC? I assume it is a desktop and that message means that the motherboard battery is either dying or not recharging. Problem is, some motherboards do not let you change the battery. If you can tell us what the motherboard is I MIGHT be able to find out if it can be replaced but if you are not keen on opening up your PC then you'll be best getting someone else to look at it. As I say, the battery could be fine but the motherboard is an issue. That means spending a bit more as you will need a new motherboard.