This happened on my 12" powerbook. I found that whenever the hardware clock was reset, it gave me bonobo errors. Try booting into mac os and resetting the clock, then going back to ubuntu.
-- 15in PowerBook G4 Bonobo errors / video failure https://launchpad.net/bugs/46702 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs