Hibernation Problems

I have my PC set to hibernate whenever the car shutdowns. But sometimes it does not Hibernate. It will boot up sayign resuming winodws but its actually restarting windows. It goes back to windows desktop forgetting whatever was loaded before i shut it down.

Anybody know of a solution for this? This is starting to be very very annoying. It hibernates 1 out of every 10 times i boot the PC. Cant understand why this is happening!