Except every once in a while, it falls apart. Windows is, unfortunately, really terrible in that way. The latest problem it had is so strange and so obscure that I felt I had to write about it just in case someone else runs into it.
First symptom: all users accounts are gone from the login screen. In fact, the login screen itself is skipped, and it goes straight to asking for the Admin password on boot.
On getting in, the "user accounts" tool shows nothing but Admin and Guest. All user accounts are just plain gone. Attempting to add the user accounts back results in an error message saying that the user "already has permission to access this computer." Well, that's unhelpful.
The parental controls section shows the accounts. The files are still there under C:\Users. Everything seems in place, but nobody can log in. Regedit shows nothing interesting. Googling around for all sorts of related phrases shows that quite a few people have experienced this, but nobody has solved it.
I just solved it. Typing "net user Jim", I can see output that ends like this:
Local Group Memberships
Global Group memberships *None
The command completed successfully.
I tried adding a dummy account, and it showed up with "Local Group Memberships" set to *Users. That's the key. For some reason, all of the accounts had been kicked out of the "Users" group, and that's why they were gone from the login screen. Adding them back in looks like this:
net localgroup Users Jim /add
net localgroup Users Madeline /add
After doing that, the system was back to normal. Ah, Windows. Thanks for wasting so many hours of my life.
