MB: Won't sleep when lid closed and power connected.

Same problem with a late2008 MBP. Fine on Snow Leopad but as soon as I upgrade to Lion it wont sleep on closing the lid.

Having same issue on early 2011 MacBook Pro with lion(quad core i7)! this is extremelly frustrating! 😢

Same issue with a Mpb (2010), I tried everything, like restart smc, pram, repair disk's permission an also run onyx's automation, no one of these actions works...

Reset the SMC

Thanks for your reply, I have already reset it, also the pram.

thanks anyway!

Does it happen even if you have no applications open and aren't connected to the internet?

in the power prefs, uncheck the "wake for internet access"

it was the Printer, when i have unnistalled, all work normally, thaks all for the replies

OK, think I found my problem.

I had to send my laptop in for repair due to a faulty screen. When I got it back it all looked OK so the first thing I did was install Lion. Then I noticed the sleep issue so assumed it was Lion causing it. I tried the pram, SMC other settings but nothing helped. In the end I reinstalled Snow Leopard, same problem! I tried from bootcamp and same problem, wouldn't sleep when closing the lid.

Doing some googling I found a post where someone has the magnet in the display fail, which is what contacts a switch in the laptop when you close the screen. To test they suggest placing a paper clip on your screen bezel until it sticks to find the magnet, then finding where it locates when closing the screen on the laptop. Then run a small magnet (i used a small fridge one) over this location on the laptop with the screen up. I did this and instantly went to sleep!!! WOOHOO! remove magnet it wakes up, repeat and OK. Close screen without magnet and nothing.

So its gone back in for repair to have the screen replaced again.

I found this solution in another post and it worked for me: I turned ALL sharing on, rebooted, then turned ALL sharing off, then rebooted. So far, so good!

OK my problem was resolved when the screen was replaced a second time. Apparently the sleep magnet in the display was faulty, so once the screen was replaced again it now sleeps fine when closing the lid 🙂

This method has worked for me. Thanks for posting this.

I've got the same problem as the original poster---brand new MacBook Pro (late 2011 latest version of Lion) will only sleep on lid-close with the power cord detached. This seems odd. I think this just happened a few days ago after about 2 months of normal operation. I have not zapped anything yet until I hear that it worked for someone else. Any clues. While I loved the screen magnet posts, this is NOT a screen magnet problem or it would not sleep when the power cord was not attached. Any ideas??

I have this exact same problem. It used to sleep fine when I closed the lid, but suddenly, maybe starting a few weeks ago it now won't sleep unless the power cord is detached. The magnet trick does not work for me either.

Having a nearly identical problem as the last few posts and the original poster. My model is an early 2008 macbook pro. Sleeps on lid close with no power cord, but when power cord is attached it will not sleep, nor go to sleep via manual sleep enabling in the apple drop down menu. I installed lion a month ago and didn't have the problem until a few days ago. Very mysterious. I've tried various solutions (PRAM, SMC, repairing permissions, clearing caches, etc), but have not yet tried the sharing options solution detailed above (about to try).

Hopefully there'll be a fix for this soon.