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I have been using a Macbook pro (newest model) for about 4 weeks with dual monitors. It has been working great using the mac adaptor to dvi. Today however, my mac will not recognize it's built in monitor while the second monitor is plugged in.

  1. Plug in second monitor
  2. The screen on the laptop goes dark.
  3. The second monitor acts as the main screen.
  4. Click "Detect displays". Nothing happens
  5. Unplug the second monitor
  6. Screen on the laptop comes on.

Any thoughts?

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I have this same problem. Did you ever find a solution besides rebooting? – Stabledog Jun 3 '10 at 13:10
up vote 2 down vote accepted

I had this same problem. By renaming the config file at /Library/Preferences/, I was able to reboot and have my Macbook Pro work normally again.

(With thanks to Dave Seaman at

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You probably need to switch between single and dual monitor output.

Go under "Displays" in System Preferences make sure the "mirror displays" is not checked.

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It's not displaying that checkbox because it acting as if there is only one display, but that display is the outside monitor. – thinksocrates Mar 15 '10 at 11:56

FWIW - I was having the exact same problem.

I tried everything to fix it - then I tried a trick from back in my days of using Windows - I rebooted.

Go figure - it worked :)

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Rename /Library/Preferences/ and reboot. – Stabledog Jun 3 '10 at 13:22

I occasionally encounter this problem, here is how I fix it:

  1. Plug in external monitor
  2. Put you Mac to sleep (Apple menu » Sleep) If you're on a laptop, leave the lid open.
  3. Let it go completely to sleep such that the light on the front pulses on your laptop. If your on a desktop Mac, let it sleep until there is no fan noise or anything - you'll hear to sleep. Takes 5 to 15 seconds sometimes.
  4. Wake your Mac up by pressing spacebar (or any key) or clicking your mouse
  5. Presto, both screens should fire up.

The preferences tip mentioned here has also worked in the past, but the steps above work without a restart for me.

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breeze has global and application window states. the states can be triggered using they keyboard and are resolution independent. pair this with sizeup and windowflow and you'll be set.

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