I'm new to Ubuntu. I've downloaded Ubuntu 12.04 twice now, and installed it onto my Lacie external hard-drive, using the Universal USB installer. My computer operates the 64 bit version. On the welcome screen I can choose between Windows 7 and Ubuntu. I click on Ubuntu, the purple screen appears but then disappears and the computer turns off. I then tried loading it onto C drive with the same result.
I'm now downloading 13.04 to see if this works better. I'm not a computer-wize so if somebody could suggest where I've gone wrong that would be appreciated.