The clock on my computer had a habit of losing one hour for no apparent reason. Finally I decided to set it ahead one hour. Sure enough, after a while I noticed it was showing the correct time. Then after another while it was an hour slow. I just looked at it this morning, and it’s showing the correct time.
A lady at worked once complained that her PC would always be a day behind in the mornings, so she would set it to the correct day, and then later in the afternoon, it would suddenly be a day ahead. So she would again set it to the correct day, only to have it be a day behind the next morning.