Accounts reset, osx damaged

Question

i have had this problem before but this is the first time its been this bad. When i opened up my powerbook and logged back in my os had reset itself back to the original settings. All accounts for programs had been deleted and reset. Key chain was empty and corrupt. Finder would craw and lock up every few minutes. I ran a disk repair and there were no problems with the hard disk. i ran an virus scan and no problems were found. The finder problem comes and goes. I havent done anything unusual with my computer, so i dont know what caused all of this. Any idea of what could be the failure or any insight to the problem.
Powerbook g4 1.67ghz 1gb ram   Mac OS X (10.4.6)  

Answer 1

Filevault. Egad.
I'm sure there are lots of people out there running filevault just fine, but I've seen so many problems with it that I'd never recommend using it. It seems to me to be something included in the OS to fit Purchase Order requirements of certain large customers, like the DOD and military contractors.
Outside of a security-clearance, need-to-know environment there's little need to encrypt everything; it certainly slows your system down and makes small file-system problems more likely to become large ones.
Consider turning off filevault if you have enough free space to do so. A better way to handle confidential data is to make an encrypted disk image of those files. See
Mac OS X: About Encrypted Disk Images and
Mac OS X: How to create a password-protected (encrypted) disk image
Good luck,
John