(Note: I hope I haven't posted this already, but these forums seem to keep forgetting I logged in. Anyway...) My friend has an iBook G4, and a while ago she ran down the battery. After putting the power supply back in and booting it up again, the screen was tinged yellow. So everything's coloured yellow, to the point you can hardly read anything - except if you press on the monitor quite hard, in which case it all turns purple instead (the opposite of yellow - random art trivia). Anyway, she reinstalled the OS, but it didn't change anything, so I'm guessing it's a hardware problem. She's phoning Apple tomorrow, but we thought it couldn't hurt to try asking here. Many thanks to anyone who can help.