Hello! I just got a pre-owned Z83-4U running Ubuntu, and I am facing a problem: the previous owner forgot the password of the admin account. I assume that I need to get into the GRUB menu as explained at Easily Reset Forgotten Password, but when I follow the instruction of pressing the SHIFT (or ESC) key, I don't get into the GRUB menu. Does anybody know what I need to do to reset the admin password of my Z83-4U ? Any help is appreciated, Holger