Question: I’ve Windows 7 Professional installed on my home computer. It has a weird problem, a “random” wake up from sleep. It often wakes up just seconds after being shut down, or wakes up in the very middle of the night when nobody is around the PC. What’s going on? Answer: First of all run the powercfg.exe utility to find out what happened last time. Command Prompt -> type in: powercfg.exe -lastwake -> press Enter. You will receive an event message with detailed description: To get the most detailed info on the device that wakes your Windows up during the sleep, type: powercfg /DEVICEQUERY wake_armed. At Command Prompt you may need administrator privilages to run this command. Usually it is your LAN interface or a scheduled task. In the Device Manager’s list of hardware categories, find the device that you want to prevent from waking your computer, and then double-click the device name. On the Power Management tab clear the Allow this device to wake the computer check box. Your computer is likely a member of home network and attached to a DSL router. There are common activities on typical local networks. Routers use ARP packets to periodically confirm the presence of computers. If so it’s no wonder your computer shows unintended wakeup symptoms. By default, Windows 7 listens for several packets when you enable Wake on LAN: – A directed packet to the MAC address of your network adapter – NetBIOS name resolution broadcast for your local computer name – An Address Resolution Protocol (ARP) packet for the IPv4 address of your network adapter – An IPv6 Neighbor Discovery packet for your network adapter’s solicited-node multicast address – A “magic packet”. A magic packet is a standard wake-up frame that targets a specific network interface. Check out your network adapter. Find the properties dialog box at Device Manager -> Network adapters -> Lan adapter section. Depending on the adapter type look for keys of – “Wake on settings”, – “Wake on pattern match” or – “Power management”. Set them to disabled. If above steps do not stop all wake up triggers than check these out: – BIOS setup for “Wake on LAN” settings. Disable it. – Power Management Options on your Control Panel: Power Options -> Change plan settings -> Change advanced power settings -> Multimedia settings -> When sharing media. -> Allow the computer to sleep. – Media Center download schedules. See Media Center -> Tasks -> settings – Windows Update manager and your security software settings (look for scheduled updates, downloads) – Windows scheduled tasks (look at Task Scheduler)

Use c:\>powercfg -lastwake utility too see what triggered the latest wake up. Use above example.