PCs are getting caught between 2 rules:

1. If there's a Windows Update pending, install it and reboot.

2. When a Windows Update fails, rollback and reboot.

So an update was released, which triggered [1] above. Then the update fails, and so [2] is obeyed.

Upon reboot, the PC realizes an update is available, triggering [1] above. Then the update fails, and so [2] is obeyed. And so on and so forth.