External monitor set as primary even when disconnected from laptop

My Lenovo X200 laptop has developed a problem recently whereby I get a blank internal screen on booting into Ubuntu 11.10. Display works normally during boot, after which the desktop is displayed momentarily before blanking out. The gnome-shell menus are not visible during this brief flicker of desktop.

It seems that the laptop is behaving as if there is an external monitor connected and set as the primary display, without mirroring or extending to the internal display.

Here are some observations:

1. If I connect an external monitor, my desktop appears on it.

2. I can then successfully use Displays (system settings) and xrandr to turn on the internal display (which is set to off), and can then mirror or extend across both displays.

3. Once I've turned on the laptop screen and set it as primary, I can disconnect the external monitor and use the laptop display independently.

4. If I boot the laptop without an external display (in which case I get the blank screen), I can switch to an alternative terminal, e.g. tty1, at which point my internal display functions correctly, but if I return to tty7 it blanks out again, and at this stage I can no longer switch to tty1, tty2, etc.

5. I can boot into Windows without problems.

I think it's possible that I meddled with some settings somewhere in the past in order to set the external monitor as the primary display when the laptop was docked. In this case I wonder if someone might direct me to potential files that I might have modified (and remind me of the changes that I may have made), so that I can revert to the original settings. This would have been a while back though, I think, in Ubuntu Maverick or Natty (and I don't know whether such modifications would persist on upgrade). This is a recent development, though, so I think there's more to it than that.

I can't think of any software installation or changes to system files that might coincide with the problem appearing.

Does anyone have any ideas for what's going on here, or how to diagnose the problem? If there's a command I can use to print out relevant system info, please let me know and I'll update the question with the details.

Open the run dialog by typing Alt+F2

Then type rm ~/.config/monitors.xml and press Enter

We use a lot of Lenovo's in our business but most have a Nvidia display card as opposed to an Intel like the X200. We use a secondary external monitor as the primary monitor and in the beginning experienced the same problem as you are currently experiencing.

The way we resolved the problems was a two step process, firstly in the BIOS under Display, Graphic Device we changed 'Integrated' to 'Discrete'. Then secondly, and unfortunately this is where the solution veers off your path, is that we downloaded & installed the latest drivers from the Nvidia website, this provided an additional Nvidia configuration utility like the one you would find in Windows and the management of primary & secondary monitors was easily achieved.

That's about all I have for you unfortunately, there are a few additional settings under the Display heading in the BIOS that may also help.

Best of luck.

milo

In my case, the root of this problem was Jupiter, which I'd installed some time ago for power management. Jupiter has some options for adjusting display settings, including output device, and these are saved and restored on startup. Changing the Jupiter 'Video Displays' to 'Internal Display Only' has corrected the problem. I might switch this to 'Enable Both Displays', as it's probably necessary to have my external operating when connected.