\ubuntu\winboot\wubildr.mbr suggests you're using WUBI, which is a way to install Ubuntu onto a file stored in a Windows filesystem rather than on a separate partition. WUBI is good for trying out Ubuntu, but it's a bit weird and inflexible compared to a more conventional installation. Of importance to you, I don't know offhand if WUBI is compatible with EFI, which you're almost certainly using if the computer shipped with Windows 8. (If you've installed Windows 8 yourself on an older computer, though, all bets are off with respect to BIOS vs. EFI booting.)
Looking at your partition table should answer some of the questions and enable you to move forward down the correct path (WUBI vs. a standard installation; EFI vs. BIOS). I recommend you boot to a Linux emergency disc and run the following text-mode command:
sudo parted /dev/sda unit s print
If you've got multiple hard disks, repeat that for each one (/dev/sda, /dev/sdb, etc.). Post the results here, or post a link to a Web page with the results.