Comment 16 for bug 201318

I'm having a similar problem on my laptop running Hardy. If I boot on AC, the gnome-power-manager notification icon seems to indicate that that I'm running on AC but when holding the mouse over the icon, the tooltip indicates that I'm running on battery. If I unplug the power cable and plug it back in again, both the icon and tooltip correctly indicate that I'm running on AC.

I first noticed that something strange was going on when I tried to debug a problem with gnome-screensaver only blanking the screen instead of showing my screensaver - it turned out to be because gnome-screensaver also thought I was running on battery when I'm actually on AC.

running acpi -v (or cat /proc/acpi/ac_adapter/ACAD/status) correctly shows that AC is online.
 hal-find-by-capability --capability "ac_adapter" | xargs -n 1 hal-device
shows: ac_adapter.present = false (bool)

I'll upload output from
  gnome-power-bugreport.sh
  hal-find-by-capability --capability "battery" | xargs -n 1 hal-device
  hal-find-by-capability --capability "ac_adapter" | xargs -n 1 hal-device
before and after unplugging and reconnecting the power cable.