Why oh WHY was this computer 5 days and 3 hours and 20 minutes off?

This was not my computer so I did very little in the way of finding a solution. I have no idea what OS it uses. Windows 10, I assume.

The day before the dates and times were right. This day it said it was Sept 13, but it was Sept 18.
The clock was off by an odd number, like 3 hours and 20 minutes slow.

I did click on the date and time on the lower left of the computer screen. I tried to reset it to the proper dates and time, but it didn’t take it.

The time was particularly odd, as it couldn’t have been anything as simple as being set to the wrong time zone.

Any ideas?