The original question was different, but I have actually provided an answer to this question before. See my post in the question "Always display the last / default user Windows 7 welcome screen" - it explains how to set up UAC and hidden accounts together so you can authenticate to the account via UAC but not log into it from the welcome screen.
Essentially, what you need to do is configure UAC to prompt for the user to enter both their username and password manually, allowing you to enter a username which is hidden from the login screen but still enabled. Instructions on how to do this are on the linked post.
In the meantime, it should still be possible for you to recover the account without doing a full reinstall. Open a command prompt (cmd.exe
), and type runas /user:USERNAME regedit.exe
, where USERNAME is the name of the administrative account. It will prompt you for that user's password; enter it and hit enter. This will open the registry editor running as that user, from which you can go in and revert the changes you made, adding back the account to the login screen.
Re-read your question and noticed that you said run-as won't work. What happens when you try booting into safe mode? I seem to recall that with Windows 7 Home Premium, the built-in administrator account is disabled by default, but is enabled in safe mode, allowing you to log into it and make changes. Unless you have hidden the built-in account in addition to whatever account you set up, this may work.
Finally, if all else fails, you could try running a system restore from the recovery console. Boot onto your Windows 7 installation disk, and choose to "repair a windows installation" instead of install. You can select your installation, then will eventually get to a screen where you can choose to do a restore. This should change the registry back to how it was before you made the change, if it has an old enough restore point. Your files will not be modified by a system restore, although some system settings might be.
It turns out that this is a known issue.
KB2345131: The logon screen appears two times when you resume Windows 7 from Sleep or Hibernation
The logon screen may appear two times. Therefore, you have to enter your credentials two times.
This issue occurs when there are multiple pending lock signals to be processed when the user is logging in. In this situation, the WinLogon state machine logs the user off.
Microsoft has released a preliminary hotfix. Because it is only preliminary, and most installations do not experience this problem, the hotfix has not been released in the normal automatic updates channel, which is why the problem hasn't been fixed automatically
yet. You can download the hotfix from Microsoft and install it manually.
I installed the hotfix on our computer which was experiencing this issue, and after three days the problem has yet to reappear, so it looks like this fix works.
Best Answer
Go to Power Options and select your active Plans settings and go to advanced settings
the Option
Require a password on wakeup
should be set asNo
See if this fixes your problem, you will need to do this for all plans that are used on your system.