UEFI Dual-Boot - Ubuntu 12.04.3 + Windows 8.1 (One GPT HDD) Hello, I'm having trouble setting up a dual-boot (Ubuntu 12.04 LTS and Windows 8.1) in my ASUS K55VM laptop's hard drive disk (500 GB). I was mostly following tutorials for doing this, but at some point something has gone wrong. Up to now, I have followed these steps: I formatted my HDD into GPT. I clean-installed Windows 8.1. I didn't prevent Windows from choosing the partitions to use and it created these partitions: A Recovery partition (sda1). An EFI System Partition (sda2). A Microsoft Reserved Partition (sda3). A Windows Data Partition or C drive (sda4). I reduced the Windows Data Partition via Windows' Disk Management. I made a bootable USB Stick with Ubuntu 12.04 LTS from ISO, using Universal USB Installer. I created these partitions for Ubuntu: A Boot partition, mounted at /boot (sda5). A Root partition, mounted at / (sda6). A Swap partition (sda7). In Device for boot loader installation I chose: /dev/sda. Then, when I rebooted, it went straight into Ubuntu. So I installed Boot-Repair, and clicked on Recommended Repair. It automatically did its job without asking for anything. I rebooted and Grub showed up, with a lot of options. At this point I had a decent dual-boot setup; Ubuntu and both Windows entries worked fine: Ubuntu. Windows Boot UEFI Loader. Windows UEFI bkpbootmgfw.efi. I executed this command: sudo grub-install --force /dev/sda5. Then I tried to make Windows 8.1's Boot Manager the main boot manager, so that I could choose which OS to boot into from a menu. I downloaded EasyBCD on Windows. It showed 2 Ubuntu entries and 1 Windows entry. I went into BCD Deployment tab and clicked on Write MBR. At this point, I went into BIOS and made Windows Boot Manager the first boot option. When I rebooted, I got a black screen with the message efidisk read error, and then (I guess) it switched to the next boot option, which is Ubuntu, resulting in Grub showing up. From Grub, Ubuntu entry is working and so are both Windows entries. If I choose Ubuntu, it normally boots into Ubuntu. But if I choose Windows, it goes into Windows' boot manager. In Windows' boot manager, a menu shows up: Ubuntu. Ubuntu. Windows 8.1. If I choose Windows, it boots into Windows without any problem. If I choose Ubuntu, it boots into Grub (back to step 14). Here's my BootInfo Summary: http://paste.ubuntu.com/6698171/ Windows Boot Manager is clearly not working as expected; I can't directly boot into it and I can't boot into it from BIOS either (efidisk read error again). If I want to boot into Windows I need to boot into Grub first, which is the opposite of what I wanted. I need help at this point. What is the best thing I can do? Is there a more reliable and/or simpler way of acomplishing a satisfying dual-boot for this situation? Can someone provide a way for going back to step 8, where I had a more efficient dual-boot setup? If only I could undo what I did with Easy BCD and skip Windows' Boot Menu... Can someone provide a way to fix this mess? Thanks in advance and sorry for the length of this, I wanted to be exhaustive.