Forwarding this bug from Ubuntu reporter Onno Timmerman:
http://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/417614

[Problem]
when switching from laptop screen to my dell screen 1900x1280 it gives a blank screen. Also on startup it gives blank black.

[Original Description]
laptop dell E4300
dell port replicator
screen del 1900x1280
ubuntu 9.04

problem: when switching from laptop screen to my dell screen 1900x1280 it gives a blank screen. Also on startup it gives blank black. 

Workaround:
First switch from screen by truning laptop screen off go to resolution 1280x1200 on the monitor. Work for about 10 minitus and then switch the screen to 1900x1280.

extra:
Don't leave your computer for more then x minutes else you never know if you need to repeat the process to get the native screen resolution of your 24'


Architecture: amd64
DistroRelease: Ubuntu 9.04
Package: xorg 1:7.4~5ubuntu18
PackageArchitecture: amd64
ProcEnviron:
 SHELL=/bin/bash
 PATH=(custom, user)
 LANG=nl_BE.UTF-8
ProcVersion: Linux version 2.6.28-15-generic (buildd@yellow) (gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4) ) #49-Ubuntu SMP Tue Aug 18 19:25:34 UTC 2009
Uname: Linux 2.6.28-15-generic x86_64
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare