As a security precaution, all homegroup computers must have synchronized clocks. Ensure that the date and time is correct ...

As a security precaution, all homegroup computers must have synchronized clocks. Ensure that the date and time is correct on all computers that are joined to the homegroup or that you would like to join to the homegroup. You can set the clock by opening Date and Time in Control Panel or by clicking the clock in the Taskbar.