It is true, beamers and ubuntu are having some problems.
When i first connected a beamer to my HP portable, I tried the FN+F4 button without any result on the screen.
I was looking around and found a partial solution to my problem. First you have to adjust de xorg.conf file:
sudo gedit /etc/X11/xorg.conf
Look for the section
Section “Device”
Identifier “Intel Corporation Mobile 945GM/GMS/940GML Express Integrated Graphics Controller”
Driver “i810″
BusID “PCI:0:2:0″
EndSection