PC won't sleep

Version: XP, Vista, 7

If your PC won't stay asleep it's often because a device is configured to bring it out of standby when triggered. Identify the culprit by pressing the Windows key and [R], type "cmd" and press [Enter].

Type the following line and press [Enter]: powercfg –devicequery wake_armed

Now press the Windows key and [R] again, but this time type "devmgmt.msc" to open Device Manager. Find any devices listed earlier, then double-click them and look for an Advanced or Power Management tab.

Check if the device is allowed to bring the PC out of standby – if it is, untick all the boxes that wake it. Click OK, close Device Manager and test it worked; repeat the process if necessary.