Finally gave up, headed back to my parents' house to return the car. Apple folks said to see if the problem recurs. When I got here to my folks house, I turned on the Powerbook on a whim to add their new wireless network I set up at lunch on my laptop, and... the entire screen turned pink-hued.
Edit: The pink went away. I have given up for the day. I am home, I am putting the computer on a table and leaving it running to see if problems occur, and I am going for a walk.