I am unable to access any user when signed in as administrator. If I go to SETTINGS, ACCOUNTS and select SIGN IN OPTIONS, the Window closes. If i run "netplwiz" I can't access any other user account. .I am trying to eliminate the requirement to sign in using a password. This morning when I attempted to sign in it would not accept my password and when I changed the password, it would not accept them and required that I enter a new password. Every new password I entered it said it was a previously used one when in fact it wasn't. Virus?