I recently tried to install Ubuntu on my Sony Vaio laptop (Windows 7, 64 bits). I downloaded the .iso file from Ubuntu website and burned it on a DVD.
But when I booted the laptop with the DVD, I got first the keypad icon, then chose the language and the choice whether to Install or Try Ubuntu. Whatever choice I made, it seems that it stops working, I got a black screen, I could not hear the DVD turning, etc...
I also tried to boot with a USB, same story. And I also tried to boot another computer from the DVD and this time I worked. So I don't think the CD wasn't burned correctly.