From my MSDN feeds regarding error;
Once you create a build-in Administrator account, you can manage other user account settings.
a. Press "Windows + R" key on the keyboard and select “Command prompt (Admin)”.
b. At the command prompt, type net user administrator /active:yes, and then press ENTER. .
c. Type net user administrator <Password>, and then press ENTER.
Note: Please replace the <Password> tag with your passwords which you want to set to administrator account.
d. Type exit and then press ENTER. Log off the current user account and login to Administrator account and check if it helps.