I've recently bought a Packard Bell imedia S 2870 with Windows 8 on. After manually installing Ubuntu 13.04 ('something else' option), the PC would boot straight to Windows.
I tried to reinstall the grub via ChRoot--following instructions indicated in various forums: e.g. https://help.ubuntu.com/community/Grub2/Installing#Reinstalling_GRUB_2 (but to no avail)--and then, after, using Boot-Repair--I went for the reccomended repair settings--, which generated the following URL (http://paste.ubuntu.com/5978031/) and invited me to make my BIOS boot on the sda2/EFI/Ubuntu/shimx64.efi file. After rebooting, the error message in the subject line above appeared, and I was not able to set any such sda2/EFI/Ubuntu/shimx64.efi as the default boot device when I accessed the BIOS.
I have had a look at similar threads without finding anything fit for purpose.
Any suggestions? Thanks