Hey guys just had my comp shite the bed two times a couple of months apart due to a bad hibernation image this prevented the computer to boot past the grey apple screen. message read "hibernation image is too old by xxx seconds use forcekey ...." the first time we just entered /sbin/fsck -fy in the safe mode dos screen, but this last time it didnt work and I just ended up having wipe and reformat and reinstall os x.... anyway, does anyone know the cause of a bad hibernation image, so that I might be able to prevent this whole thing in the future?