Comment 13 for bug 274938

hal-find-by-property --key button.type --string lid | xargs -n 1 hal-device

that should give you information about the state of the lid as seen by hal.

I would be interested if you got the machine to a stable state then ran

  killall gnome-power-manager
  gnome-power-manager --verbose --no-daemon 2>&1 | tee gpm.debug.log.txt

and then tried to reproduce the bug, attaching the gpm.debug.log.txt file to the
bug after resuming when you get it to suspend.

If the problem doesn't seem to occur after restarting g-p-m then I wonder if opening
and closing the lid a few times slowly before unplugging ac will cause it to trigger.

I would check the state of the lid as seen by hal as soon after startup, and then
perhaps add a monitor on its state to see if it changes without the lid being closed.

Thanks,

James