One of the reasons is maybe the time of your computer is not correct, you can check the time located in the right side of the taskbar (for Windows), it usually gets the old/past year, then you can correct the year, month, date, hour, min to solve the problem.
The time is not correct maybe because of CMOS battery is low, so if you shutdown your computer, it will not be able to store the data (in the BIOS). Change the battery with new one.
