I just formatted my Samsung Ultrabook and installed Ubuntu 12.04 via USB using rufus to create the bootable USB (my ultrabook don't have a cd/dvd reader). The problem is, when the instalation finish and ask for a reboot, it skips the hdd boot and start via USB right away, and when I remove the USB it says "All boot options are tried. Press F4 key to recover..." Wich I suppose says that I don't have a valid OS installed in my HDD. I reinstalled in the same partition overwriting the former ubuntu installation (the live cd recognized the previous installation). Same problem. After that I followed the instructions from here: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows And the same happened. I don't know what to do, and I can't use my ultra anymore. Help pls!
EDIT: I tried installing Windows 7 in half my hdd. Everything ok. But when I installed Ubuntu in the other half, I can't access to any of them. At startup says: "error: file not found. grub rescue>" However, I can access both OS with the bootable Super Grub Disk in my pendrive. Using the Super Grub I managed to install Lilo in my Ubuntu partition. After installing Lilo, the computer booted normally only windows 7. With further google hunting I read that this can be a grub problem, and messed up with grub settings via terminal. After that I can't access any OS, neither I can get to boot with lilo (can't find config files). Now I know it's a problem with the boot files, not the ubuntu partition. What can I do? Is there any other boot type that may work for me?