A hardware device might be keeping your computer awake. USB flash drives and USB mice are common devices that can keep your computer awake. Make sure that you have the most current drivers all of your devices.
To prevent a device from waking your computer
1.Open Device Manager by clicking the Start button Picture of the Start button, clicking Control Panel, clicking System and Security, and then, under System, clicking Device Manager.? Administrator permission required If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
2.In the list of hardware categories, find the device that you want to prevent from waking your computer, and then double-click the device name.
3.Click the Power Management tab and then clear the Allow this device to wake the computer check box.
4. Click OK.