EquiNOX

I hate laptops now... I encountered same experience as yours, At first I never understood what it was just until I found out it was battery.... Question, when you had that problem was it plugged or was it battery operated? If battery, its more likey your battery may need replacement.
To clear on this one.. Nicad or Lithum battery does last when recharge but lifespan is 2 years or some hours depending how much you use your laptop so when they worn out it would cause frequent shutdown on your system.