I just got off the phone with AppleCare on this issue. Diagnosis: bad hard drive, or more likely, a bad hard-drive controller. (Possibly in addition to some corruption of the database storing user information.) The way we got to that was to try all the usual fixes, then try to reinstall OS 10.2 with an Archive and Install option. But the installer couldn't see the hard drive (though Disk Utility could see the drive and repair). Then we tried an erase with Disk Utility. It could not unmount the hard drive. The reason to think it's not the drive itself is that the the drive was replaced last September with similar symptoms. Fortunately we have AppleCare and I can see the drive when the iBook is started up in FireWire target mode. I love this iBook, and my son loves it, but it has been into the shop three times for hinge repairs and now twice for hard drive problems, all since late sumer 2001. Stephen Hart http://eugraph.com