I today I installed Ubuntu 10.4 on my 13in PowerBook G4 from a live CD. When I first booted from the CD I had no problems. I clicked Install Ubuntu and went through the process normally. When I finished installing it, it restarted, I logged in and everything was fine. But anytime after that when I restart, it starts the boot process, and when it reaches the screen that says "Ubuntu" with the loading dots, the display cuts out and goes black. I can tell it's only the display and not the computer because shortly after I hear the standard startup sound. Is there anything I can do?