I have the same problem with a laptop (a second time)
Is a ubuntu-12.04.1-desktop-amd64.iso
Usb created with Ubuntu Live USB creator
I have enabled UEFI-Support
Laptop stucks in blank screen.
After power-off cycle it shows only black screen
It is the second laptop and I do not think you can return to the warranty, you can reset the BIOS on this computer? help please
(sorry for my English, I have been supported by google translator)