MBP 2011: external displays not detected automatically

My late-2011 13" MacBook Pro generally doesn't automatically detect external displays. At work or at home, I plug it to either a 23" Cinema Display (2005) or a 24" LG display using a Mini DisplayPort / DVI adapter.

Sometimes auto-detection of the display works out-of-the-box (notably, the first time I plug a display after a reboot), but most of the time I need to manually click "Detect Displays" in system preferences.

My two monitors work perfectly, my MDP/DVI adapter works too (confirmed by cross-testing with other Macs, other displays, other adapters). The problem only comes from my MacBook.

Does anyone experiences the same issue?

• Model: 13" MacBookPro8,1 (late-2011)
• MacOS: 10.7.3 (11D50 -- problem occurs since 10.7.0)
• Graphics card: Intel HD Graphics 3000
• Software that might affect the issue: iScreen 3.0.0 (even though the problem also occurs with iScreen uninstalled).

I solved that problem by connecting HDMI cable to another input of my external display. I don't know exactly what's the difference but it works for me.

Here are some troubleshooting steps you could try to isolate the issue:

• Run all software updates on both the iMac and MacBook Air. A lot of times there are firmware updates that address issues like this.

• Reset the PRAM on the MacBook Pro by restarting the computer and holding

  ⌘+⌥+P+R on boot but until you hear the POST chime twice. Then you can let go and boot normally.

The PRAM stores configuration information about the displays connected to your Mac, so resetting it may be the answer for you. Try going through these steps and let me know if you're able to resolve the issue.