Hi Jule I've only found one way to fix this on my iBook 2001, and I'm sure it shouldn't work (but it does)
I added the following to a file in /etc/modutils -- #arcane i2c-majick - awooga, awooga! post-install snd-powermac rmmod i2c-keywest && modprobe i2c-keywest -- Something similar may work for you. Chris
