Does "put display to sleep" hot corner require some other specific settings? All hot corners work perfectly except for this one. Instead of putting the display to sleep it dimms the keyboard.
What's even more odd, this hot corner seems to be working fine from time to time, but it's so random I can't even tell.
I don't know if it matters, but I've recently installed fresh Mountain Lion, downloaded all updates and checked permissions.
I've called Apple Support and they told me to reset nvram. It worked for one day.