additional user account

additional user account

Hello I have a toshiba satellite series laptop running dual boot OS's Windos7 and Ubuntu. Everything is well as far as I can tell but all of a sudden when I boot into Windows I am seeing the option of opening a different account ie. (Guest account) I have never opened a guest account and upon checking the guest account is turned off. I tried to open this "mystery" account but it is password protected. Any thoughts on this weirdness?