Comment 7 for bug 298226

Hello!
I can confirm the issue - disabling the external monitor crahses X, __when Visual Effects (compiz) are enabled__.

Prerequisites:
1 you have compiz turned on
2 my monitor setup is: external monitor is on (1440x900@60Hz), laptop screen is disabled (OFF)

Steps to reproduce in Gnome 'Screen Resolution' tool:
1 switch laptop screen ON (1024x768@60Hz)
2 turn external monitor OFF
3 Apply the modifications
Result - GDM/X crashes

Work around - if you disable the visual effects before reproducing the steps, everything will go just fine.

I'll add the xorg.conf, syslog, auth.log, :o.log.1 and lspci -vvnn as an attachment

hope that helps 8)