Hi,

I'm running my MBP closed and through an external display with a wired keyboard and wired mouse (soon to be a magic mouse).

I have the energy saver settings set to...

Computer Sleep: Never
Display Sleep: 5mins

But the external display doesn't seem to go to sleep ever.

I came home today and it was on but showing the screen saver.

I had Mac Mail open but nothing else.

Any ideas what else I can check for reasons that this is happening?

Thanks!

Are there any USB devices attached?
Have you tried logging into another user account to see if it behaves the same way in there? If it sleeps in the other user account, could be a dodgy preference file in your original user account's Home folder, possibly this one...

Home > Library > Preferences > com.apple.systempreferences.plist

Ah, could be the USB mouse I have. It's a cheap and nasty Targus laptop USB mouse.

Could be causing it not to sleep possibly.

The mouse may be getting reflections back from the surface it's on so doesn't go to sleep.

Does the machine wake up if you choose Sleep from the Apple menu?

I unplugged the mouse last night and it didn't make any difference

Also I clicked Sleep from the menu and it went straight to sleep with no problems.

I'm going to restart it tonight to see if that does anything?

Could be this preference file, found within the "Library" folder at the top level of the hard drive, not your Home folder...

Macintosh HD > Library > Preferences > SystemConfiguration > com.apple.PowerManagement.plist

Drag this file to the desktop (or the Trash can), then restart the Mac - afterwards, go back into System Preferences > Energy Saver and set the relevant Sleep options again. See if it goes to sleep properly this time. If all is well, then delete the old .plist file as a new one should be created.

If that doesn't work, you could try resetting the SMC (System Management Controller) - see this Apple Support article (note the two options for portables at the bottom of the page, depending on the exact model of Macbook Pro).

Finally, if none of that helps, it's more than likely some kind of background process or hidden app that's running waiting for something to happen. For example, scanners and All-in-One printers tend to have background apps that sit there waiting for a button to be pressed on the printer/scanner, sometimes these can cause problems if they're not fully compatible with the version of OS X you're running. Check Activity Monitor to see what's running in the background - also check System Prefs > Accounts > (click your user name) > Login Items for any suspect items that could be lurking around, stopping it sleeping properly.

Ah yes.

I just did a quick check this morning with putting it to sleep.

I'll have a look at the file tonight.

OK, I've also added some bits to my earlier post, you might want to check those too!

Brilliant!

Deleting the PowerManagement file and restarting worked perfectly!

Thanks!

Nice one.