Macbooks Prompting Password Change on Login

On our college campus a large majority of our Macbooks are prompting people to change their password upon them attempting to log in even when their passwords are not expired. The popup asks them for a new password and for a hint. They can hit cancel and try to log in again and it still might prompt them. There is no apparent rhyme or reason to when the popup occurs and when it just lets them log in like normal. Sometimes hitting Switch User or restarting the Mac helps but that seems to be a coin toss as well. This has been happening for around a month now and updates on their Mac don't seem to help. Any help would be greatly appreciated.