grub2 - Ok Ubuntu HDD boots to black screen

This question is similar to this other one in that I get the same result, however I am booting an apparently fine HDD.

For four days I have been booting Ubuntu 14.x on a very inexpensive laptop. I did a format and clean install on a WD Passport (will not buy again) external HDD. It works beautifully. I've just gotten home from traveling and I'm attempting to boot off the external drive on my desktop Win 8 machine. This is where the issues start.

In my boot options I can see the drive and select it to boot from. However, in my bios settings I cannot set it as a default boot option. I see only the other drives on the system. I have Both UEFI and Legacy set in my options. So, I cannot for the life of me figure what is wrong there.

If I manually select the external as my boot drive I get only a black screen with a white cursor as mentioned above. If I reboot from the thumb drive that is my installer I can successfully use the 'Try without installing' option'; that works fine. I am certain that it is not an integrity issue with the external dirve because I can see the files (in trial Ubuntu) and I can still boot the laptop off either.

TL;DR

Ubuntu external drive boots fine on laptop but not desktop.

Bios will allow manual boot of drive but it is not visible in default boot settings.
UEFI and Legacy option is set.

External drive boots to black screen with white cursor. Nothing else.

Desktop will boot pen drive with "Trial Ubuntu" and installer just fine.

Laptop will still boot either.

I am using AMD and ATI hardware but the system will run trial Ubuntu fine and I cannot seem to get into grub anyway.

How can I get my external drive to boot successfully on my desktop?

EDIT

After talking to Xen2050 in the comments below I think that grub is either crashing or not running. This is my best guess due to the fact that after editing /etc/default/grub to always boot with nomodeset (on my laptop) I still can't boot past the black screen or access grub on the desktop. This is my current grub.cfg with a delay added (see comments) just in case that helps.

Could this still be a driver issue?

EDIT 2

I'm now attempting to boot with nomodeset, radeon.modeset=0', andgrub_gfxmode=1024x768x24`set in the defaults. I also attempted this from the working laptop. Still cannot boot or get into grub or tty.

That is a lot of lines in that grub.cfg, I use a real basic one for my multiboot USB's, pretty much a set timeout & set default & a few menuentry's...

I tried cutting away all the graphics-related stuff, and functions too, and was left with what might work as a no-frills grub.cfg to try out (keep the original as a backup, though it is pasted to that github website I'd do a mv on the original anyway):

set timeout=-1
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-5165d33f-4b1c-41e9-9ca9-e1c831348abc' {
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
linux /boot/vmlinuz-3.16.0-29-generic root=UUID=5165d33f-4b1c-41e9-9ca9-e1c831348abc ro quiet splash
initrd /boot/initrd.img-3.16.0-29-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-5165d33f-4b1c-41e9-9ca9-e1c831348abc' {
menuentry 'Ubuntu, with Linux 3.16.0-29-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.16.0-29-generic-advanced-5165d33f-4b1c-41e9-9ca9-e1c831348abc' {
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
echo 'Loading Linux 3.16.0-29-generic ...'
linux /boot/vmlinuz-3.16.0-29-generic root=UUID=5165d33f-4b1c-41e9-9ca9-e1c831348abc ro quiet splash
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.16.0-29-generic
}
menuentry 'Ubuntu, with Linux 3.16.0-29-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.16.0-29-generic-recovery-5165d33f-4b1c-41e9-9ca9-e1c831348abc' {
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
echo 'Loading Linux 3.16.0-29-generic ...'
linux /boot/vmlinuz-3.16.0-29-generic root=UUID=5165d33f-4b1c-41e9-9ca9-e1c831348abc ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.16.0-29-generic
}
menuentry 'Ubuntu, with Linux 3.16.0-23-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.16.0-23-generic-advanced-5165d33f-4b1c-41e9-9ca9-e1c831348abc' {
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
echo 'Loading Linux 3.16.0-23-generic ...'
linux /boot/vmlinuz-3.16.0-23-generic root=UUID=5165d33f-4b1c-41e9-9ca9-e1c831348abc ro quiet splash
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.16.0-23-generic
}
menuentry 'Ubuntu, with Linux 3.16.0-23-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.16.0-23-generic-recovery-5165d33f-4b1c-41e9-9ca9-e1c831348abc' {
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
echo 'Loading Linux 3.16.0-23-generic ...'
linux /boot/vmlinuz-3.16.0-23-generic root=UUID=5165d33f-4b1c-41e9-9ca9-e1c831348abc ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.16.0-23-generic
}
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry 'Memory test (memtest86+)' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
knetbsd /boot/memtest86+.elf
}
menuentry 'Memory test (memtest86+, serial console 115200)' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 5165d33f-4b1c-41e9-9ca9-e1c831348abc
else
search --no-floppy --fs-uuid --set=root 5165d33f-4b1c-41e9-9ca9-e1c831348abc
fi
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}

That might be able to at least get GRUB to display something...