
Some weeks ago I wrote a patch to fix the issue, it has been applied to the main development trunk of gnome-power-manager so there will be no problems with next versions. However, we have to manually apply it to the current version included in Ubuntu. Here you can find more informations about the issue and the patch that fixes it.
If you don't want to manually rebuild the ubuntu package of gnome-power-manager to apply the patch, you can use the .deb package fixed and built by me.
You can find it on my repository.