On my G4 PowerBook with OS X 10.2.6 the System Preferences -> Sharing ->
Personal File Sharing option is getting turned off from time to time.
This morning it was off, so I turned it on and then 'locked' the System
Preferences (the option at the bottom with the lock icon) and few hours
later it was off again (no restart in between)!!!

Has anyone any idea what might cause this behaviour?