My iBook G4 will not start-up. The screen comes up with the apple icon, the drive "churns" for about a minute, then stops leaving the icon on the screen. Using the iBook G4 Software and Install DVD, I ran the Apple Hardware Test and got an error message: Invalid Node/Rebuilding B-Tree. The repair, however, failed. I've tried transferring my files to my MacBook with a Firewire but the iBook G4 icon does not appear on the MacBook. My next thought is a more powerful disc first aid program. Any thoughts? This is my first problem with the iBook and I'm a bit stumped. Thanks.