Let me preface everything by saying I am new to Windows 7, but I thought others who may also be new may find this useful.
I've worked with various Windows OSes since Windows 3.1. I've worked with Windows security in one role or another since Windows NT 3.51 came out. Now I just set up my first Windows 7 Ultimate system (actually my first windows 7 system at all). I've learned over the years that it is NOT a safe practice to login as the Administrator. For this reason I set up Windows 7 the same way I set up all my windows XP computers.
When I first received the computer Win7 went through some basic setup. I created accounts for users and put the ones that needed it in the power users group. I changed the name of the built-in administrative account from Administrator and assigned the account a password. I then took the default user setup when windows starts, out of the administrator's group. Since I thought I could always get to the Administrator's account I didn't think it was a good idea to leave too much latitude in other accounts.
The Author made several common mistakes in the above sequence; for instance, the old "Power Users Group" is no longer recommended, and there are certain security advantages to not
having a password on the (highest level) Administator account. This article is about how the Author corrected things after having made errors.][/step]
I performed some other security tasks and logged off the machine. When I went back in I wanted to install some software. Since I was no longer in the administrator group I did not have permission. So I tried the way I always did it before. I right clicked on the program and selected "Run as Administrator" (it used to be just "Run As ..."). I was presented with a dialog box that asked for the administrator's password but would not let me put in the administrative account name. So I could not get administrative access. I thought this would not be a problem. I logged out and tried the way I always accessed the administrative login on XP computers - press Ctrl-Alt-Del twice at the login prompt - but nothing happened.
Here I was at kind of a loss. Since I hadn't done much with the computer yet, going back to the beginning would not be a problem, but it was frustrating. It turns out that in Windows 7 the Administrator's account is disabled by default, which is good for security, but wasn't going to help me. I tried enabling the admin account using roughly the instructions on these pages:
Windows 7 - Built-in Administrator Account - Enable or Disable
Enable the (Hidden) Administrator Account on Windows 7 or Vista
But that would not work because it said I did not have enough privileges to execute the command.
: Booting into safe mode (press F8 on startup) actually let me login as the renamed administrator and execute the instructions above.
: Same as Solution 1 except instead of enabling the admin account, as administrator I could add another user to the administrators group (more secure than Solution #1)
: Since I was early in the installation, I also decided to see what would happen if I rolled back to the factory install using Dell's DataSafe bundled with the system. This worked beautifully (of course I did have to start my configuration over).
I have had to update my security practices to better coincide with the Windows 7 platform. If you are used to WinXP, and know what you are doing, take it one step at a time when configuring Windows 7.
Windows XP security configuration and Windows 7 security configuration are different. Do NOT go about it in the same way or expect the same things to work.
You actually DON'T need the Administrator account in Windows 7 to be enabled, using the "Run as Administrator..." option is better
Remember the Administrator's account on Windows 7 is disabled by default.
The easiest way to troubleshoot a problem with administrative privileges seems to be to boot into safe mode and follow instructions on enabling the administrative account, adding the administrative group to another user, or performing what ever task you need to do in that mode
XP and 7 are different enough that you need to be careful how you configure things
Other EE articles on Windows 7 I found useful:
Godmode on Windows 7
Windows 7: Two Steps Forward, One Step Back
Run programs under Windows 7 like in XP