What OS is the laptop running?
You could try this:
1) Disconnect AC
2) Shutdown
3) Remove battery
4) Connect AC
5) Startup
6) Under the Batteries category, right-click the Microsoft ACPI Compliant Control Method Battery listing, and select Uninstall. Do this for each instance (I had 2 batteries installed, so 2 instances. Most users will only have 1).
7) Shutdown
8) Disconnect AC
9) Insert battery
10) Connect AC
11) Startup
But! I had the same problem with our Dell laptop, whilst still under waranty we had the Dell tech replace the battery, charger and the motherboard! the problem went away! for about 10minutes after the tech guy had left!!!
After searching on the web, I decided to re-install the OS (theres some suggestion that its a known 'bug' within numerous microsoft OS's) After doing a re-install of the OS, no problems at all
