At some customers I see a problem occasionally with Windows 7 loosing the domain membership and users can’t login.
There is a lot of things you can try, but the easiest way is usually to remove the machine from the domain and then re-join it.
But as many organizations wants to secure their environment, they might randomize the local administrators password and disable it. Then we have a problem….
But an easy way to enable the account and reset the password is to use Trinity Rescue Kit. Just download the ISO from http://trinityhome.org and burn it to a CD-R, boot from the CD and a Linux distribution is starting up in Live mode. You will then be presented with an easy menu of choices where you will find “Windows password resetting”.
There is other great stuff on this CD as well, like a file commander, file server and a virus scanner. Let’s say your OS has crashed an you want to save your files, just enable a temporary file server and browse the share from another computer on your network and copy everything.