David: I was fairly certain he had the built-in admin account which was why I suggested the solution I did. However, I now realise I should have asked him to verify his account details so that this was clear to everyone. This is simply done by typing wmic useraccount list full into a command prompt and it will reveal the details of all accounts on the system.
See this tutorial for more details: User Account Details - View in Windows 10
I have seen a number of cases of this happening with upgrades from earlier Windows versions and I do not know why it happens. A repair install with an in-place upgrade does not always help because the user ends up with the built-in admin account again.
I'm in the process of acquiring a Win 10 ISO so I can maybe try the repair install thing later.
I don't recall activating the built-in Administrator account at any time. If it's so destructive, perhaps there should be more protection or it shouldn't even be there. I installed Windows 7 from a disc and typed my name in for my username when the installation was done.
I still don't believe you have been using the built-in admin, It does NOT get enabled by itself.
But if you really do, leave it alone. Don't use it unless you are in emergency.
Yes, I have already created a new account; I wasn't referring to a third account. I already tried making the new account an administrator and after doing so I receive the same error about the built-in administrator account. Presumably every account that I give administrator privileges will have the same problem. I suggest that the error message is wrong and that this has nothing to do with the built-in account which is probably actually still disabled.
The problem was fixed by doing a "repair install". Thanks for your help.
Thanks for reporting back on the solution. Create a restore point and a system backup so that you can recover quickly if it ever happens again.
Please be informed that Modern Apps do not run on the built in admin account. You need to create a new account and set it as admin if you want to run these apps as administrator. This feature is by design, made for security reasons.
Please make sure of the followings :
1. Create another admin account for emergency.
2. Get an external hard drive and do system Image backup regularly and save it to the ext hdd. That will save you a lot of heartache. I had used it many times to restore my computer when I had problems I could not fix.
3. Create system restore points regularly.