Fatal error when doing clean install Ubuntu 14.04 desktop

[I.Q. Ut]

Installing on a software raid (after sudo apt-get install mdadm and creating a Raid0 array usings Disks). No way how I try to install Ubuntu it doesn't work. I get a grub-error

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubiquity 2.18.7
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CasperVersion: 1.340
Date: Mon May 12 16:57:36 2014
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper only-ubiquity quiet splash --
LiveMediaBuild: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
 TERM=linux
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[I.Q. Ut (iq62ut36)]

Please let me know which other files to attach. I'll reproduce the problem.

[Ubuntu Foundations Team Bug Bot (crichton)]

Exception during installation:
May 12 14:56:21 ubuntu /plugininstall.py: Traceback (most recent call last):
May 12 14:56:21 ubuntu /plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1770, in <module>
May 12 14:56:21 ubuntu /plugininstall.py: install.run()
May 12 14:56:21 ubuntu /plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 78, in wrapper
May 12 14:56:21 ubuntu /plugininstall.py: func(self)
May 12 14:56:21 ubuntu /plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 241, in run
May 12 14:56:21 ubuntu /plugininstall.py: self.configure_bootloader()
May 12 14:56:21 ubuntu /plugininstall.py: File "/usr/share/ubiquity/plugininstall.py", line 1026, in configure_bootloader
May 12 14:56:21 ubuntu /plugininstall.py: "GrubInstaller failed with code %d" % ret)
May 12 14:56:21 ubuntu /plugininstall.py: ubiquity.install_misc.InstallStepError: GrubInstaller failed with code 1
May 12 14:56:21 ubuntu /plugininstall.py:

[I.Q. Ut (iq62ut36)]

Additional information:

x64 architecture0
2 SSD disks
No difference if I do auto partition (whole disk) or manual partition
No difference if I use LVM in combination with auto partition (whole disk)
Doesn't matter which partition I nominate for bootloader in manual partition
Seems to be changing to an i386 command during install (I read earlier bug reports stating the same)

Steps I did take
a) let the hardware raid configure the RAID0 (so in the installer you see one disk)
b) build-up the RAID in the liveCD using Disks (after installing mdadm)

[I.Q. Ut (iq62ut36)]

This bug is open for some time. Any progress or daily build I can use to see if the problem is mitigated?