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I have a MacBook Pro, late 2010 model, with a display-port out that I use with the DP->DVI adapter to drive a Dell monitor as my secondary. I run Mac OSX Lion 10.7.3.

The secondary monitor is positioned above my laptop screen, so I've arranged it like that in display preferences.

When I have the secondary monitor plugged in (and powered on), quite often (but not every time!) the MBP will not sleep when I shut its lid.

When I open the MBP again, quite often (but again, not every time) the MBP's monitor will not be detected, and the secondary monitor will be where the lock-screen prompt is. The secondary monitor will also be running at a lower resolution than it's capable of.

I will then need to open display preferences, and then detect-displays before both screens are back to normal - and then rearrange all the windows that have shrunk down.

This is getting dull.

This seems to have been getting more prevalent with Lion vs Snow Leopard.

How can I get the MBP to remember that its primary monitor is always the laptop screen? I'm at a loss to know how it can forget about that one, really.

I did install some software called Display Maid after googling for solutions to this sort of problem, but I haven't been able to make that improve this problem - it's supposed to restore windows to the positions that they were in when it noticed a certain display configuration, but I haven't been able to get that to make a positive difference. Display Maid isn't the problem, though; it was evident before I installed it.

Additionally, how can I get the MBP to remember the resolution of the attached, not-changing monitor?

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The easy answer is, do not plug in the secondary monitor until the primary is up. The MacBooks are set up to function when closed using an external monitor, keyboard, and mouse, so you can plug everything in, and tuck the machine out of the way. In typical Mac style, this is supposed to "just work", but sometimes it gets confused as to what's actually happening. If, for instance, I plug in my power, ethernet, monitor, and USB (in a line from back to front), I usually end up with the external as primary, as the OS 'sees' the external before everything else starts. The other fix is to check the "Show displays in menu bar", and use it to 'Detect displays" when you need it to find your laptop lcd again.

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The MBP just gets shut when it's not in use; it's actually rare for it to be mobile and unplugged. So messing with the cables is rare and I'd like to avoid it. – Peter Mounce Mar 29 '12 at 9:35

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