internal monitor not shutting off when lid closed + external monitor connected

[rrgjl]

So, like the title says, when I connect my Macbook Air to my fairly new Dell U2212HM monitor through Display Port (mini to regular cable), and I close the lid, the integrated monitor does not shut itself off anymore. I'm pretty sure it used to, but I'm not sure how long I've had this issue. Can't be much longer than a month or so.
I've tried having the Macbook opened and then connecting the cable + turning on the monitor, I've tried connecting while lid was already closed (in which case it actually doesn't even respond most of the time), and I've tried connecting and then rebooting. The last one seems to solve the issue sometimes, but not all the time.
I've also tried using a different user account btw, no influence there.
What could be causing this problem? I'm running an up to date os x lion on the newest version of the Macbook Air 13".

 

[sammich]

Does your computer go to sleep when you close the lid? With/out the monitor connected?

 

[rrgjl]

Yes it goes to sleep when there is no monitor connected.
When I use detect screens when the external display is connected and working, it blinks for a second, but keeps showing 2 active screens even though the lid is closed.

 

[rrgjl]

I finally found something referring to it.
It's basically this issue, and it's good to see I'm not the only one experiencing it: https://discussions.apple.com/thread/3435078?start=0&tstart=0
Unfortunately it seems there is no solution yet, or at least no one has a solution in that thread.

 

[Zetaprime]

Does your computer go to sleep when you close the lid? With/out the monitor connected?

Have you tried a nice little app called InsomniaX? (http://www.macupdate.com/app/mac/22211/insomniax) It's designed with clamshell users in mind. I use it mostly so I can close my computer so that cats won't be stepping on the keyboard while doing long downloads. It allows you to configure lid sleep and idle sleep and the screen does shut off when the lid is closed even though the computer is still active.

 

[JesseW6889]

Same issue with my 2011 Air. It didn't always do this though... This is my 3rd Air though, so I'm not sure if this one ever worked right or if it was my older one, running Snow Leopard. Either way, it drives me NUTS!

SOLUTION: The only work around I have found is to shut off the laptop, plug in the external monitor, turn it on and when the apple logo shows up on the grey screen, shut the lid and keep it shut, it will boot using only the external monitor!

 

[stu.h]

Wierd, mines behaves exactly as it should.
Is yours the Summer 2011 version or an older one?

 

[philxor]

This is a known issue, it's fixed in Mountain Lion. I don't think Apple did any QA when it comes to external monitors with Lion.