I have an older computer that I was setting up and a DOS screen popped up initially requesting a password. I typed in a password and was asked to confirm, which I did. All seemed to be accepted until the next time I tried to turn on the computer. Again on a black screen I was asked to type in the password...using the very same password I was denied access. I am the only one in the house, so it could not have been changed. How can I override the password??