What were you doing at the time the laptop went into hibernation, gaming, web stuff? what surface was the laptop on and did you hear any abnormal fan noises from it?
I might suspect offhand it may have overheated, it may be a hard drive fault, graphics card fault or possibly (although less likely) something else
I think I'll suggest trying a hard drive diagnostics tool like SeaTools for DOS http://www.seagate.com/support/downloads/item/seatools-dos-master/
and checking the hard drive's health.