Some computers have issues with Windows hibernation mode. To get the computer back up again you should just hold the power button down until it shuts off completely. Some laptops won’t shut off even if you do this. When this happens you have to take the battery out to get it to turn off. Make sure it is not plugged into the wall when you do this otherwise it wont work.
Once you get the computer back running again you may want to disable hibernation if it seems like its going to keep happening. Go to Control Panel and then to Power Options. Change the hibernation section to never. You may want to try standby as an alternative. Standby saves all your running applications and documents into RAM while hibernate saves them to the hard drive. Hibernate uses less power from your battery, but it will take you considerably longer to get the computer back up. If you always plug the computer in then you may want to disable standby and hibernate since you really dint need them while plugged in.