I have energy saver preferences set to go into sleep mode in 15 minutes. after 15 mins only screen sleeps, and sleep indicator led is on( not flashing). I can manually put it to sleep. several things that I have tried with no luck: 1. Reset PRAM and SMC 2. Reset Energy Saver by trashing some plist files. 3. Format partition and reinstall OSX 4. Remove all usb devices 5. Disable ethernet port. 6. Try it in safe boot. Since energy saver doesn't work even on a new OSX, I think maybe it has something to do with the firmware. But auto sleep works on windows 7 ... it's a really weird problem. the only solution that will work is a 3rd party software called " please sleep". Is there any solution to fix this problem rather than use please sleep?