What would make my mac lock

I leave my Mac running overnight. Several times over the past month, I've come down and the screen saver is dead and the background of the screen is white. When I provide my password to unlock the screen saver, I get a note that accountsd wants my password to unlock my "login" keychain. If I provide it, dozens of other programs then ask for my password, like this:

There 50 to 100 more of these, and it just doesn't stop. I can't bring up Terminal to reboot the system, the finder is basically unusable. I can ssh in and do a sudo halt or I can just hit the power switch.

Is anybody else experiencing this? Why is it happening? How do I make it stop?

This is typical of a keychain error or issue or just an inconsistency in caching of auth tokens that indicate the grace period to not ask for a password after you log in once.

Causes can be system keychain, user keychain, login keychain, time and date inconsistencies, system corruption.

You’ll need to isolate and troubleshoot these one by one if entering the passwords becomes troublesome.