The problem is related to the motherboard. The battery power is not reaching the RTC (Real Time Clock) circuit and hence when the machine is powered off, the timer is shut down and starts again only when you power up the machine. To rectify this problem, you will need to have the motherboard repaired. But finding a good engineer to have the board repaired is difficult. If it is repaired successfully, then you are lucky, else the board could even get further damaged and replacing it would be a costly affair. We would advise you to either get it repaired through a good professional engineer or the manufacturer's service center itself, or live with the issue till you upgrade the computer in near future and buy a new motherboard.