Tigger4me my Acer Aspire 5630 sometimes goes into hibernation lock, usually when trying to recover from a software crash, screen goes blank and there is no recovery.
It, so far, has always responded to a complete power down, by that I mean removal from the power supply and removal of the battery. after about 20 minutes refit battery and turn on - ops normal till the next time.
It's other party piece is complete loss of time and date but that is easier to sort out.