Raenny

Hi, I am in desperate need of some help. I have a pc that was acquired used that has some software that I need to be able to access without losing. The problem is when I boot this pc up it comes up to a log in screen that has a list of 6 or so domains. I have reset the admin password with a 3rd party tool but the pc will always try and access one of these domains and will never find it. I know the log in and pw are good but it doesnt find the domain and will not continue to boot to windows. Is there a way to reset these domains so that this pc knows it is a stand alone pc? I have also used a dos boot up disk but once it boots to dos it doesn't recognize the hard drive. Any help would be greatly appreciated.