text: Could you be a little more specific? How does it change exactly? If it's resetting every time you shut the computer off then citalopraming has got it right, you need a new cmos battery, which is just a coin cell battery on the motherboard that supplies a bit of power to keep the clock right and the bios settings intact while the computer is off. If it's just changing by a few minutes every few days that might mean that the clock on your motherboard is a bit fast or slow, and every week or so the clock automatically syncs itself with an internet time server, and changes back to the correct time.