I am unable to install Ubuntu on my MacBook Pro. I have it written to a USB drive, and I get up to the language select screen before everything just freezes. Cursor won't move as I use the touchpad, arrow keys won't work, keyboard doesn't respond, nothing. Not sure how to fix this since I can't even install anything. When I try to "try Ubuntu without installing", the same thing happens on the desktop. No response from the OS whatsoever, it just freezes.