My laptop shuts itself off after inactivity. I've seen the other postings about overheating but that is not the case here. The laptop goes into sleep mode, or hibernate, but can't be brought balk out; it then eventually shits down suddenly. When I re-boot, I get a Windows message stating that the system was shut down improperly.

What can I do to stop this? My laptop was literally perfect. Something has changed. But what?