Now that you mention it, I seem to recall that the hibernate option in power saving in XP can be problematic. Mine's turned off and whenever I do an install, I make sure it's turned off without even thinking about it any more.
IIRC, power saving is handled through the ACPI, which is implemented by the BIOS and chipset device drivers. You could try updating the BIOS and all device drivers while you're at it, along with all patches and updates. Or just turn the damn thing (hibernate) off.
