I have a 8.2 MBP with a 1680x1050 screen and a 6490M graphics card. I'm trying to boot from a usb stick ubuntu live. I'm able to get to the ubuntu menu, asking to install or start live boot, but when I select live boot I get a black screen( backlight is still on but entire screen is black). I've waited at that screen for quite some time with no luck. I haven't seen a similar problem on the forums. Anyone have any advice?