Why won't my MacBook detect an external display?

Agreed. I connect an external display every day when I get to work without any problems. I make sure the display is on, and my laptop is not asleep. If I unplug the monitor and then close the lid on the laptop too soon after (within about 5 seconds) I notice that when I next wake up the machine it tends to be confused.

In summary: laptop awake, monitor on, then plug/unplug, wait a few seconds.

I had the same problem with a brand-new MacBook. I went to the Genius Bar at my local Apple store, and they reset something. They sent me an email with an URL, I'll try to find it.

I too have a new (3 month old MacBook) so I'd love to get that URL. In the mean time, I'll try the best practice of unplugging first. Thanks guys!!

I can second the "unplug the monitor first" advice. I had this problem too, and since I've started unplugging the mini-DVI connector (and letting the monitor re-adjust to single-display before closing the shell), I haven't had this problem since.

I have a related problem. I unplug my second display, wait, but the macBook doesn't realize the second display is gone. Detect display is no help, and Gather Windows brings up the secondary display control panel as if it were still there. How do I get the macBook to realize the second display is gone short of rebooting?

I have a related problem. I unplug my second display, wait, but the macBook doesn't realize the second display is gone. Detect display is no help, and Gather Windows brings up the secondary display control panel as if it were still there. How do I get the macBook to realize the second display is gone short of rebooting?

Macbook Pro 10.4 had a problem today which relates to this problem above. The Laptop worked fine projecting a presentation at an offsite location. When I returned to Work and reconnected to a large projector the Macbook Pro would not detect displays. No matter what I did. I rebooted, changed resolutions and nothing but Blue screen. I had to use an older Macbook and Target disk my Macbook Pro to run my presentation. Now I can't seem to detect displays otherwise.

I don't know if this is related or not!

I have a macbook with OSX.5.3, just over three months old. I have two external monitors in different locations that I connect to with the little Mini-DVI to VGA cable adaptor.

Until recently this has worked fine.

I *think* the problems started after an update but can't be sure. Occasionally I can connect to one or the other monitor and it works, but most of the time I just get the flashing blue screen on both internal and external displays.

Its like my externals are seeing the mac, but the mac isn't seeing the externals.

The times when it does work (I try every day, just about), are so random and infrequent, I can't detect a pattern.

Plugging and unplugging whether the mac is on or off makes no discernible difference. Rebooting with cable in has worked a couple of times, but most of the time doesn't.

Um. Help? Please? Anyone?

I'm stuck with this same problem - I'm seriously getting tired of my Mac - it seems like nothing really works well and there's too many little design geeks trying to jam their bad ideas into one box.

Seriously, I just want to change between two identically resolutioned monitors - they're positioned differently and what works for me - the way "I want to use my Mac" - is to switch the cable between the two.

However, switching an external video cable appears to require a comprehensive shutdown/startup - meaning I have to close about 35 windows, get out my notebook and take notes about what I was doing (isn't that why we invented computers!), change the cable, reboot, then get back to where I was.

Changing a monitor cable should take less than an hour!.

Has anyone figured out how to get an early MacBook Pro (the 2G limited build) running a 10.4 system, to successfully implement VGA without rebooting, etc. Or is this "yet another" Macintosh Mistake?

After upgrading from 10.5.4 to 10.5.5 I went into the same problem too.
My external Display (Apple Cinema) can't be detected by my MacBook.

It's been different versions of X, isn't it about time you guys at Apple fixed this?

Now my Mac Mini is going Vista / Windows Media Center full time.

Hello, same problem here.
After last update, external display is not detected anymore.
Tried any kind of thinks. Reboot, with and without displacy connected, resting display, etc.
Lost external display.

Hello,
I had same problem some days ago.
Asked Apple dealer here, they said I had REINSTALL OSX, and get it to version 10.5.4 (I had 10.5.5).
I did not like it at all, so I waited a new system upgrade.
Today, I upgraded OSX to 10.5.6.
Problem has (apparently) disappeared.
I was a torture !.
I Can't not believe that apple site has nothing about this issue, or nothing clear at least.

No way.
I was apparently.
Problem persists, an worst.
Apple, are you there ?.

Same issue here. 10.5.6 update fixed the problem, then a few days ago, out of nowhere my screen started blinking black, and in a few minutes I lost the display. Now no matter what I try I can't seem to get the external display to work in any reliable manner. I have spent days of wasted time on this issue, and everything used to work fine on mac os 10.5.4.

Apple created the problem, but has shown little responsibility in trying to resolve the issue in a timely fashion, and have in no way reassured customers of their competence in dealing with such bugs.

Hope someone finds a way out.

Same issue here, just trying to keep the topic alive :)

My display won't return after I opened the lid while working with an external screen and putting it to sleep.

I had this problem and just got used to unplugging my monitor before sleeping the laptop.

Seems to have fixed the issue.

In my case, external display configuration is lost after rebooting, randomly.

I have found a solution for my blackout problem, maybe it will work with someone else:

http://getsatisfaction.com/apple/topi...

I have the same problem too. Unplugging before sleeping doesn't work, what works is usually rebooting. I hope apple fixes this quickly, I am on 10.6.1 Snow Leopard

MacBookPro 13'' has the same problem. Detects the external screen. Then laptop goes to sleep. I wake it up. External monitor is not working. I have to wear out display mini port by removing it and plugging it back.

Hello? Anybody in this Company would respond? We may arise this issue loader in many sites? Maybe some professionals could give a solution.

IT'S HAVE BEEN MORE THAN A YEAR WITH THE SAME PROBLEM!!!!