Recently my Windows 7 64-bit PC has started waking every night from hibernation around 3:30am. I have done the following to try and figure out what is causing the issue with no luck:
- Examined the Windows Event logs. Nothing is noted
Ran powercfg -lastwake and that reports nothing
- Wake History Count - 1
- Wake History 
- Wake Source Count - 0
Ran powercfg to find what devices are armed for wake. Interestingly, this reports two items (I've already unchecked the "Allow this device to wake the computer" in device manager): The keyboard and something called the "eHome Infrared Receiver (USBCIR)". This is a desktop PC and it does not have an Infrared received, so I'm not sure what that device is. Suffice to say it does not have the option to "Allow device to wake..." available in Device Manager.
- C:\powercfg -devicequery wake_armed
- eHome Infrared Receiver (USBCIR)
- HID Keyboard Device
My next step is to disable the Keyboard from wake, but I'm not convined that's the problem.
This is on a Dell XPS435 if that helps anyone.