I am using Ubuntu 11.10 on VAIO . Whenever I unplug the charger from my laptop, there comes a dialog showing "battery critically low" and system suspends, even when the charge is 100%.
It is possible this is a bug. There are several bug reports filed reporting similar things. Check out here : https://bugs.launchpad.net/ubuntu/+source/upower/+bug/531190
The battery might have remembered its charging state. Try shutting down, then remove the battery from the laptop and wait some time. Then put it back, and power on the laptop. It should now show that the battery is empty. Also, try suspending and waking up the laptop, sometimes suspend / wake-up have weird effects which can only be undone by suspending/resuming again.
Open dconf editor application and navigate to:
org > gnome > settings-daemon > plugins > power
Then uncheck the use-time-for-policy key.