Laptop shuts down no warning as battery is low.

Since I have my laptop Acer Extensa 2303LC installed with Windows 7 Pro, the laptop simply shuts down without warning when the battery power gets too low.

I have gone through the Power Options. There does not seem to be anything I can do to rectify it.

When it has XP installed, it always warns as the battery is getting low.

I wonder if there is something I could have missed.