MacBook Pro doesn't detect external display after Lion upgrade
This is from my own experience, I have macbook pro with lion and a dell monitor, I connect via mini displayport to VGA connector, if I connect displayport first to my macbook and then monitor's vga to displayport to VGA, it won't work, I don't know why but maybe some internal implementation detail, just go in this order
- switch on both devices
- connect monitor's VGA cable to your mini displayport cable,
- connect mini mini displayport to you macbook.
- wait for a few seconds, it works every time.
Mine did this because I had Air Display installed (yes, Air Display). I uninstalled that app and everything works now.
Shut down the MacBook. Start it up with the external monitor connected. It should recognise it. Had same problem on Mountain Lion with a projector I had used many times before. Was supposed to be showing a film to a bunch of kids in the Youth Club and had to give up. My wife discovered the next day that restarting with it connected fixed it.