I have a (seemingly rather exotic) Dell Latitude XT2 notebook running Lubuntu 12.04, fresh install.
Tried to get the power button to work as expected (opening lubuntu-logout, just as I think it was meant to be out-of-the box), but no success: power button does nothing but forced power-off on long press.
Here some more information, please ask if something more could help:
I have a Compaq(HP) laptop. I connect it directly to the main power source without the battery, since my battery does not hold charge. I notice that on switching on the power button, the laptop starts booting with the power led on. Then it stops, on its own restarts. This time with the power led off but the boot sequence completes.
While switched on, the power led is still off.