I get this after trying to reinstall grub using boot-repair:
Grub2 (v1.99-2.00) is installed in the MBR of `/dev/sda` and looks at
sector 778209992 of the same hard drive for `core.img`, but `core.img` can
not be found at this location.
Here is the full summary. Basically my computer just boots into Windows EFI without showing the GRUB bootloader. I'm guessing that GRUB is not installed on the EFI boot partition, even though I tried every option. I'm using Ubuntu 14.04 64-bit and Boot-Repair (for saucy) along Windows 8. Also I have an older version of Ubuntu(13.10)
bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi
fixed everything! – lamino Oct 09 '14 at 15:08bcdedit
in command prompt, it shows you a list of keys and values for (in my case) two boot managers. Apparently the command above assigns GRUB to the "path" entry, stored either directly to the EFI file, or a config file in the same partition. So on boot EFI looks for the "ubuntu" entry instead of Windows Bootloader. – lamino Oct 10 '14 at 00:15