This issue started happening after I updated to OSX Mavericks.
I have an external monitor connected to my Macbook Pro (2010), and everything works just fine and dandy.. until my Mac doesn't have any activity for a bit and turns off the screen (NOTE: not the whole Mac is asleep at that point, it's just the screen).
Then when I swoop around on my trackpad to wake it back up, it won't recognise the external monitor the way it used to. Suddenly the arrangement is flipped (i.e. it's now below my Mac rather than above it), and the resolution is switched to 800×600 rather than the normal 1680×1050.
When I then pull the plug and plug it back in (while my Mac and its screen are wide awake), it finds its old configs again and fixes the resolution and arrangement.
Has anyone experienced anything similar, or is there a fix available? Or should I just consider this an unresolved bug, report it to Apple and hope for the best?
Best Answer
The fix I've adopted is to visit the Display section of the System Preferences. Hold the Option key to reveal the Detect Displays button. Click it.
The connector on my laptop has ended up a bit loose after years of unplugging and reinserting. Using System Preferences is probably kinder on it, until some kind of fix is forthcoming.
(There used to be a menu bar icon for displays, which included the Detect Displays option - but now that I have need of it, it appears to have been removed. Apple knows best, I suppose, and who am I to argue. Perhaps I am just plugging it in wrong.)