I am running Windows 8.1 on my system (Dell e6520) and the symptoms are this: My PC won't sleep or hibernate. It the screen turns off, but the fans just run and run, and after a little while, it completely shuts down, and when I start it back up, everything is closed, like it was a fresh boot/restart. I'm have a weird issue with outlook described here and the fix works fine - modifying a registry value. The weirder part is that after my computer fails to sleep or hibernate, and it starts back up, the registry value is GONE, like I never modified it, and thus the outlook error message is back. I thought maybe a graphics driver was preventing the sleep/hibernate, so I attempted to uninstall the NVIDIA graphics driver and control panel. HOWEVER, once the computer fails to sleep/hibernate, the NVIDIA graphics driver and control panel appear BACK on my system, like I didn't uninstall them. What could be happening here? I really need to be able to sleep/hibernate so I don't lose work or my work state, and these issues are really concerning. What I've tried, without success: Uninstalling graphics driver mentioned above Disabling hibernate and using sleep disabling/re-enabling hibernate Disabling startup items Sleeping as local system admin account disconnecting all USB, network, and bluetooth devices