Ibook G4 Keyboard and Trackpad problem HELP

I'm having a problem I would like to run by you. I have a Ibook G4 /1.2 ghz/ 12" screen. It 's keyboard and trackpad don't work. I can use the ibook with an external usb keyboard and mouse. The thing is if I start from a ubuntu install disk everything is fine. And I would be happy with that, but i don't know how to set up the modem for Ubuntu. Any way further when I put in the osx hardware test disk and test it . it says everything is fine and while I'm still booted from that disk the trackpad and keyboard work just fine , but as soon as I reboot to OS X they go back to not working. I've tried booting from an external firewire drive with the same results. I have also since tried to do some combo updates and when I try to go from any comboupdate as in 10.4.6 through 10.4.9 the keyboard and tracpad work fine but a whole new issue comes up immediately. After the update restarts the ibook I can see keyboard and trackpad are working but when the system reaches full reboot within 20 seconds it goes to sleep. I can wake it just for a split second but then it proceeds to go back to sleep. I have done many complete installs trying for a fix so there isn't any important info to loose. Right now i'm running it on 10.4.1 with an external keyboard and mouse. The previous owner said it started this after he fell with it in his backpack, but it doesn't seem to me to be a mechanical issue. Just thought you might have some ideas for me to try??? If you could try to send me a reply to my email larrybdl@localnet.com