So my wife's been having this problem (perhaps the same, maybe just similar), and I finally got to looking at it today. I could get it to reproduce in a specific way.
MacBook Air aluminum case 13". Mac OS X 10.6.8.
Symptoms: as you're working along, screen blanks out, but then comes back again shortly thereafter.
Running on battery power. Didn't really test plugged in.
Steps to reproduce:
- Closed lid. Presumably, this put machine into sleep mode. Timed closure for 15 seconds
- Opened lid. Screen came on. Left system alone.
- After about (maybe exactly?) 15 seconds, screen would blank out and then come back.
Depending on your circumstances, if you just opened up your machine and started working, you might perceive this to be a “reset” of the screen right in the middle of what you’re doing.
I checked a few things as best I could from prior posts.
Hot Corners: I checked the settings, and found nothing was enabled.
No magnetic fields nearby that would suggest lid closure to the system.
I saw posts suggesting MS Word or Excel were involved, and she uses Word a lot, but after lots of trials of shutting down this or that application, I found it reproduced even after having quit all applications (visible through command-Tab application switching).
I also tried changing Energy settings (bright vs. dim display when on battery) and Display settings (sleep after 1 minute, sleep after 10 minutes) and screen saver timing. None made a difference.
In the end, I came across an article that talks about resetting the System Management Controller:
http://macs.about.com/od/usingyourmac/qt/Resetting-The-Smc-System-Management-Con troller-On-Your-Mac.htm
After taking those steps (basically for this kind of MBA: plug in, left shift+control+option+power, restart), I tried to reproduce the symptoms again using the close lid, wait, open lid, wait – and it didn’t blank out after 15 seconds any more!
So that SMC restart appears to have solved my problem. I'm curious if others who are having a blank screen problem can reproduce their problem similarly, and whether the SMC restart works for them.