On my SP4, HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\54533251-82be-4824-96c1-47b60b740d00\8baa4a8a-14c6-4451-8e8b-14bdbd197537 is still '1' and it is working fine.
I would suggest before trying out the steps suggested by Rvacha, try a Restart (NOT Shutdown and turn...