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.