My stock XP machine was hibernating fine, and I had it set to hibernate on low bat and sleep. The Hibernate key worked fine. It always came out of hibernate fine. This afternoon the machine ran out of battery, and XP decided to shut down instead of hibernate. The machine restarted fine. Now though, when I hibernate, the machine says "preparing to hibernate" and then locks up. Even the mouse is unresponsive. I checked the disk in case the hibernate file was corrupted. Where is the hibernate data stored, can I just delete the file and have it recreated or something? UPDATE- I fixed it. Turned hibernation off in the control panel. defragged the drive, turned it back on, reset the power settings, now it works. Don't know why.