When the computer is powered up, the first user is able to sign in with his/her password. after that, the computer changes the user passwords. the next user must power down the computer and back up in order to sign in with the correct password. what is happening and how can I stop this? I teach high school and this only happens when using a Dell Optiplex 755. All of the other Dell's I have do not have this problem.1 person got this answerI do too