I am trying to install Ubuntu 12.04 by creating a USB Boot Disk. I am using a 500 GB External Hard-drive ("Elements"). I get through the first part of using the start-up disk creator. I select Ubuntu 12.04 "Precise Pangolin" as the ISO, and my external hard-drive, which has 150 GB free, as the disc to use. I hit "Make Startup Disc". It asks me for authentication before I can copy files, and that part works. Then after copying files, it asks for authentication again to install the boot loader. At this point, it immediately says "Failed to install the bootloader." Any idea why I am having a problem?
I know with Ubuntu Quantal (12.10) usb-creator-gtk is currently plagued with Bug 915626. But your using 12.04
My recommendation would be to start fresh. Open the 'Disks' manager and format your usb drive and delete the current partition. Then recreate a New FAT32 partition and format.
After that is complete try the usb-creator again, see if you make any headway. If it still fails might I suggest a workaround.
In the Software Center look for a program called, "UnetBootin"
Install it and simply select the "Diskimage" bullet. Make sure the 2nd dropdown says "ISO" and press the button to select the ISO you wish to burn onto your disk.
Make sure that your USB Drive is selected under "Type" and the Drive is properly set to /dev/sdb1/ (Assuming your usb disk is /dev/sdb)
Let me know how that turns out!
Check your partition format . If it was