I tried to boot 12.04.1 amd64 version from an USB stick (EFI booting), and again end up with a scrambled desktop. I tried then "nomodeset" option which boots fine for a short while and then ends up in a command prompt.
I did "dmesg | tail" and here are last few lines:
I then checked /var/log/Xorg.0.log and Xorg.failsafe.log and here are some lines:
init: lightdm main process (1833) terminated with status 1
init: plymounth-stop pre-start process (2652) terminated with status 1
init: failsafe-x main process (2529) terminated with status 1
Any hints how to move forward are highly appreciated.
(EE) [drm] failed to open device
Loading submodule "vbe"
Loading submodule "int10"
(EE) VESA(0): V_BIOS address 0xd00 out of range
(EE) Screen(s) found, but none have a usable configuration
p.s. I also tried 12.04.1 amd64+mac - this iso however boots in BIOS compatible mode only and won't boot from an USB