Install Ubuntu 14.04.2 LTS alongside Windows 8.1 Dual-Boot on RAID Acer S7 question marks installation popup error "???"

While installing Ubuntu, the option 'Install Ubuntu alongside Microsoft Windows 8.1' doesn't show up.

After properly configuring the computer's UEFI settings and partition the drives, the Install Now button shows a small popup error window with a '??? ???' title, a '??? ???' error message, and an Ok button and the installation halts.

When I close the window by clicking Ok, it takes me back to the screen before the partition configuration. This becomes a never ending loop and I'm not able to complete the installation.

How can I successfully install and boot Ubuntu 14.04.2 LTS and Windows 8.1 Pro, on an Acer S7 191-6400 Ultrabook?

I found my own solution detailed below:

1. Install a fresh copy of Windows 8.1 Pro from the original Microsoft DVD and make a bootable USB drive, as described here. During the Windows setup process, choose custom type of installation, in which you're allowed to configure partitions. Erase all the existing partitions except the computer's recovery partitions and created a primary partition large enough for your needs, and install Windows 8.

   If you do not want to install a fresh copy of Windows, I strongly encourage you to make a backup of your current windows setup and shrink one of your partitions to make room for the Ubuntu operating system as described here.

   Leave the Windows Fast Startup activated but disable the UEFI BIOS Secure Boot in order to finally boot into Ubuntu.

2. Download the Ubuntu 14.04.2 LTS 64-bit ISO image and create a bootable Live USB drive, as described here or here.

3. To boot into the Ubuntu Live USB drive, click Restart in Windows while holding down the Shift key. From here you have two options:

   1. Sometimes, the Use a device option will show up in the upcoming screen, which will automatically boot into the Live USB drive.

   2. Sometimes the option is not there and you have to select Troubleshoot, Advanced Options, UEFI Firmware Settings, and Restart.

      Once in the UEFI BIOS, either go to the Main tab and enable F12 Boot Menu or go to the Boot tab and move your USB drive to the top of the list. Exit the BIOS, saving the changes, tap the F12 key, and boot into the Live USB drive.

4. When the GNU GRUB screen comes up, select Try Ubuntu without Installing and boot into a Live instance of Ubuntu.

Now this is the critical part that makes the difference and has not been made explicitly clear anywhere else.

5. Here, go to 'Dash Home' and search and run gparted. When the application first starts, you might get a Libparted Bug Found! error popup:

   The backup GPT table is not at the end of the disk. 
   This might mean that another operating system believes the disk is smaller. 
   Fix, by moving the backup to the end (and removing the old backup)?
   

   Click on Fix and another 'Libparted Warning' window popped up, saying:

   Not all of the space available to /dev/mapper/isw_hhidjbh_HDD0 appears to be used, 
   you can fix the GPT to use all of the space (an extra 512 blocks) or continue with the current setting?'
   

   Click Fix once again, and then one last 'Libparted Bug Found!' comes up:

   Invalid argument during seek for read on /dev/sda
   

   Clicked Cancel on this one!

6. Once the GParted application finally runs, create a root and a swap partition, as described in here, hit Applyand you'll get All operations successfully completed. Close the window without saving the details. Then another Libparted Bug Found! pops up saying again Invalid argument during seek for read on /dev/sda.

   Clicked Cancel and close the GParted application.

7. Now you're ready to install Ubuntu. Connect to the WiFi network and run Install Ubuntu from the desktop.

8. Followed all the steps as described in here up until the 'Installation Type' window, where it asks if you want to Erase disk and install Ubuntu and choose Something else. This is the screen where the option to Install Ubuntu alongside Microsoft Windows 8.1 should have come up.

9. In the next window, you'll see the partitions that you created with GParted in step 6. Select the root partition, hit Change, changed Use as: to ext4 journaling file system, check Format the partition, and selected / as the Mounting point.

10. Set the Device for boot loader installation to /dev/mapper/isw_hhidjbh_HDD0, matching the partition names in the list. Then select the root partition in the list and click on Install Now. And this will finish the installation successfully without errors! :D

11. Boot to the bootable USB drive with the Windows setup once again. Follow the initial instructions up until the point were you can configure the partitions and quit the installation and when the computer restarts, it will boot into Windows 8.1 Pro without problems.

12. To boot into Ubuntu, reboot and go back into the UEFI BIOS, disable Secure Boot as described in here, and enable F12 Boot Menu as described in step 3.

13. Now you can boot into both operating systems by tapping the 'F12' upon restart and using the boot menu.