Two Administrator accounts

Help! I think I messed up my Vista.

The gaming monster finally came back from full warranty surgery, and of course I immediately plugged everything in and started getting it set back up the way I want it to be. A part of the warranty deal was that we get to hang on to our old hard drive, and they will put in a new one, with a clean install. They did. Nothing on there but clean Vista and a single Administrator account.

Me being me, I renamed Administrator to Alpha Centauri, and then created one account for me and one for The Guy. I then went on to update Vista, and rebooted when prompted. After being online for roughly half an hour, it occurred to me to install an antivirus. So I rebooted after the updates were done, and installed Avast.

Now, every reboot, instead of getting to an account select screen, I got an error message saying "name or password of the account is incorrect". Weird. Since I was in Alpha Centauri, I decided to rename it back to Administrator, to see if that would fix it.

It didn't. It told me there is already an account named Administrator. Baffled, I went to the account select screen again, via a restart, and what do you know. There are two Alpha Centauri accounts! They take the same password, and they have identical desktops and desktop settings.

How badly have I messed up, and can it be fixed?

 

This morning I booted to safe mode, and tried renaming the account there as well. I got the same error. When trying to reboot, Vista tries to go into the Administrator account, fails because the username/password is wrong, and when I go to the account selection screen I see four accounts, the two I created for us to use, and two Alpha Centauri.

Once logged in, I only see one Alpha Centauri in Manage Accounts. I don't have the option to delete one of duplicates, since it only shows as one when I am logged in.