When waking Macbook Air 2012 from the Login Screen, the display flashes, then works normally. Mildly concerned.

Same display flash on my 2011 Macbook Air. Turning off powernap on battery off does not reslove issue. Has to be a software issue as I cannot remember my Air doing this before 10.8.

Ed

Apple released a firmware update shortly after releasing Mt Lion. The Powernap settings were greyed out when Mt Lion was first released. The firmware update fixed the problem, enabling the Powernap settings. I set Powernap On for both power adapter and battery. And I experienced the same problem of the screen flashing twice on wake. Changing the setting Enable Power Nap on battery power to Off, fixed the problem.

Macbook Air mid-2011

This seemed to have worked for me as well. Thanks!

I'm having the same issue. Mid 2011 MBA and the screen flashes when waking up from sleep. I do not have Power Nap enabled on battery power and it still flashes.

Noticed the issue on 10.8.2.

Disabling PowerNap did not rectify the screen flash on wake-up... somewhat concerning... Ed

Same issue here, noticed it the very first morning after upgrading to Mountain Lion. Question to others experiencing this issue... how many of you have an SSD HD installed in your Macs? just playing with some ideas..

I have. After all, I'm a MacBook Air user.

I too have a Macbook Air, 13 in and have the flash issue. I thought something was wrong, but that seems to be my only issue with M. Lion. I have never enabled Power nap so... that isn't the issue. Hope someone comes up with an explanation/solution. It is an annoying new phenomenon. Glad to know it is not just my machine.

I've got the same issue on my mid 2011 Macbook Air 2011 - never before upgrade to Mountain Lion - disabling power nap does not resolve it for me - hoping Apple will fix this as clearly a software issue.

I've noticed the same thing, if I put my air to sleep while it's under a bit of load the screen will flash at wake the way it fashes if connecting an external monitor. Im pretty sure it's just the video card starting up or resetting.

Bizarrely my Macbook Air has stopped doing this - I turned off powernap, but it was defintely still flashing. I've since rebooted a couple of times and it no longer flashes - doesn't make a great deal of sense because I'm fairly sure I didn't make any other changes....

I was able to solve this by disabling "Show mirroring option in the menu bar when available" from System Preferences > Display

Good tip. That seemed to do the trick for me as well.

Looks like I spoke too soon. It went away after disabling the feature...but now it's back.