Just recently, my clock in the System Tray has started to lose time. Every couple of days or so I notice that it's lost many hours. It's not a major problem but it's a bit irritating when my emails start to show that I replied before I got them (maybe I have second sight or something!)

I downloaded a little atomic clock program so it could synchronize the clock over the internet, but Windows Defender kicked up such a fuss about it, even before I installed it, that I decided that discretion is the better part of valour and ditched it in case it's a nasty.

Is there an easy answer within Windows, or a safe program that will synchronize the clock with an atomic one on the internet, or do I have to get some sort of battery replaced?