So I’ve been searching around the net for an answer to a problem I’m seeing. I had this same problem on my old Powerbook g4, and for the last month now on my Macbook Pro. The problem exists with autodetection of an external monitor.
At work, the first thing I do with my laptop is dock up, that is plug in to my wired ethernet, and external monitor via DVI. For a long time this detected the new device, and would auto setup my screens to the chosen configuration. I do this often at home with my tv or an external monitor. Each one has it’s own preferences that automatically apply.
Problem is, starting with work, that stopped. It wouldn’t auto detect. If I manually run the “detect displays” it works as expected (without the whole *auto* part). Something isn’t triggering when the new monitor is plugged in.