The trackpad on my iBook G4 1.44ghz stopped working this morning! At first it went stuttery. I temporarily solved this by plugging in a mouse- without using the mouse itself, this seemed to make the trackpad responsive again. After letting the iBook go to sleep, the trackpad doesn't work at all; nothing I do seems to make it respond. I've tried resetting the PRAM and NVRAM, but this hasn't done anything. Is there anything else I can do, short of buying a new trackpad?