[Samba] Administrators SID is invalid.

[mots]

Hello,

I've got a samba 4.2 DC, which has worked well for about a month now. It
still works for all users except "Administrator".

If I login to a Windows box with the Administrator account, I can't
connect to any shares and clicking on a mapped drive returns the error
"The security ID structure is invalid".

Opening "Active Directory Users and Computers" on the Windows box
returns "The RPC server is unavailable".

Using "smbclient -L localhost -UAdministrator" on the GNU/Linux server
running samba I receife this error: "session setup failed:
NT_STATUS_INVALID_SID".

Is there a way to fix this without restoring the database from backup?

Kind regards,

mots