This is a bit convoluted but I'll explain it as well as I can. I just built a computer for which I have no dvd drive so I used the instructions and booted fine the first time from a usb drive. Installation went well but when I restarted, I could not log in. Apparently when I set it up I typoed the password not once but twice the same way. I tried just reinstalling but the computer would not boot from the usb again no matter what I did. (This is an N-alvorix mb, so its older) As as workaround, I deleted the Ubuntu Precise LTS partitions from the drive on another computer with g-parted. Now the drive which started as 500 gb shows 465 gigs and will not boot to the usb - instead it gives me a screen that just says 'grub-rescue'. Is there a hidden partition lurking or something else that might cause this?