text: my clock changes time on task bar once every few days? it never did it til i put in windows defender     maybe that will help some 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.