Your computer’s case has a power button that can be pressed to shut down or put the computer into a sleep mode. Windows 7 helps you control how the computer behaves after the power button on the computer is pressed. The function of the power button can be changed to Do nothing, Sleep, Hibernate, or Shut down.
If you want the computer to go into a power savings mode or shut down when the power button is pressed, then use the following instructions that to change the Power button behavior:
Run: Regedit
Open: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Power\PowerSettings
Then, click on every folder until you find one folder that contains the “FriendlyName“: @%SystemRoot%\system32\powrprof.dll,-251,Power buttons settings
mine is the folder: 4f971e89-eebd-4455-a8de-9e59040e7347
when you find it, open it and search for the forder that contais the “FriendlyName“: @%SystemRoot%\system32\powrprof.dll,-255,sleep button action
mine is the folder: 96996bc0-ad50-47ec-923b-6f41874dd9eb
then, open the forlder: DefaultPowerSchemeValues
you will find 3 folders. For each folder you will have 3 “files”. You need to change the value of the files (in every one of the 3 folders):
AcSettingIndex: to 3 (it is by default to 1)
DcSettingIndex: to 3 (it is by default to 1)
Then, you go back to the Control Panel:
Control Panel\All Control Panel Items\Power Options\Change when the computer sleeps\
and click on: Restore default settings for this plan
Source: microsoft.com
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