Windows 7 Ultimate x64 SP1
My Uncle complained that he was locked out of his account. He swore that he knew his password and that after installing a Windows update that he was unable to authenticate with his password. Additionally, the biometric fingerprint scanner was not allowing him access.
Without doing any further investigation, I plugged in my usb multibooter and fired up NT Offline Password Changer and cleared out the password.
I rebooted and saw this error:
The Group Policy Client service failed the logon. Access is denied. [ OK ]
The screen flashes to "Logging off..." (it tried to auto-log the primary user)
...and takes me to the log in screen.
With the password now cleared I click on the user icon and receive this error:
Windows Security HRESULT 0x8007ffff
At this point, I loaded into x64 Recovery Mode and tried to activate the built in Administrator account, but it was not visible from Safe Mode or normal boot afterwards.