Here is a quick fix. Source: http://www.digwin.com/plugged-in-not-charging-windows-vista-laptop
01. Turn off laptop.
02. Unplug AC power.
03. Remove battery.
04. Replace AC power.
05. Turn on laptop, allow OS to boot.
06. Once logged in to the machine, perform a normal shut down.
07. Unplug AC power.
08. Replace battery.
09. Replace AC power.
10. Turn on laptop, allow OS to boot. The battery should once again be charging as normal.